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Hypertext Transfer Protocol
Wykrecnumer.pl (Dialanumber.pl) was a Polish website that allowed its users to substitute any phone number for their own when making phone calls or sending text messages.
It was shut down when the Internal Security Agency deemed it a threat to national security and its owner was arrested on suspicion of cyberterrorism.
The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web.
Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text. HTTP is the protocol to exchange or transfer hypertext.
The standards development of HTTP was coordinated by the Internet Engineering Task Force (IETF) and the World Wide Web Consortium (W3C), culminating in the publication of a series of Requests for Comments (RFCs), most notably RFC 2616 (June 1999), which defines HTTP/1.1, the version of HTTP in common use.
HTTP functions as a request-response protocol in the client-server computing model. A web browser, for example, may be the client and an application running on a computer hosting a web site may be the server. The client submits an HTTP request message to the server. The server, which provides resources such as HTML files and other content, or performs other functions on behalf of the client, returns a response message to the client. The response contains completion status information about the request and may also contain requested content in its message body.
A web browser is an example of a user agent (UA). Other types of user agent include the indexing software used by search providers (web crawlers), voice browsers, mobile apps and other software that accesses, consumes or displays web content.
HTTP is designed to permit intermediate network elements to improve or enable communications between clients and servers. High-traffic websites often benefit from web cache servers that deliver content on behalf of upstream servers to improve response time. Web browsers cache previously accessed web resources and reuse them when possible to reduce network traffic. HTTP proxy servers at private network boundaries can facilitate communication for clients without a globally routable address, by relaying messages with external servers.
HTTP is an application layer protocol designed within the framework of the Internet Protocol Suite. Its definition presumes an underlying and reliable transport layer protocol, and Transmission Control Protocol (TCP) is commonly used. However HTTP can use unreliable protocols such as the User Datagram Protocol (UDP), for example in Simple Service Discovery Protocol (SSDP).
HTTP resources are identified and located on the network by Uniform Resource Identifiers (URIs)—or, more specifically, Uniform Resource Locators (URLs)—using the http or https URI schemes. URIs and hyperlinks in Hypertext Markup Language (HTML) documents form webs of inter-linked hypertext documents.
HTTP/1.1 is a revision of the original HTTP (HTTP/1.0). In HTTP/1.0 a separate connection to the same server is made for every resource request. HTTP/1.1 can reuse a connection multiple times to download images, scripts, stylesheets et cetera after the page has been delivered. HTTP/1.1 communications therefore experience less latency as the establishment of TCP connections presents considerable overhead.
The term HyperText was coined by Ted Nelson who in turn was inspired by Vannevar Bush's microfilm-based "memex". Tim Berners-Lee first proposed the "WorldWideWeb" project — now known as the World Wide Web. Berners-Lee and his team are credited with inventing the original HTTP along with HTML and the associated technology for a web server and a text-based web browser. The first version of the protocol had only one method, namely GET, which would request a page from a server. The response from the server was always an HTML page.
The first documented version of HTTP was HTTP V0.9 (1991). Dave Raggett led the HTTP Working Group (HTTP WG) in 1995 and wanted to expand the protocol with extended operations, extended negotiation, richer meta-information, tied with a security protocol which became more efficient by adding additional methods and header fields. RFC 1945 officially introduced and recognized HTTP V1.0 in 1996.
The HTTP WG planned to publish new standards in December 1995 and the support for pre-standard HTTP/1.1 based on the then developing RFC 2068 (called HTTP-NG) was rapidly adopted by the major browser developers in early 1996. By March 1996, pre-standard HTTP/1.1 was supported in Arena, Netscape 2.0, Netscape Navigator Gold 2.01, Mosaic 2.7,][ Lynx 2.5][, and in Internet Explorer 2.0][. End-user adoption of the new browsers was rapid. In March 1996, one web hosting company reported that over 40% of browsers in use on the Internet were HTTP 1.1 compliant.][ That same web hosting company reported that by June 1996, 65% of all browsers accessing their servers were HTTP/1.1 compliant. The HTTP/1.1 standard as defined in RFC 2068 was officially released in January 1997. Improvements and updates to the HTTP/1.1 standard were released under RFC 2616 in June 1999.
An HTTP session is a sequence of network request-response transactions. An HTTP client initiates a request by establishing a Transmission Control Protocol (TCP) connection to a particular port on a server (typically port 80; see List of TCP and UDP port numbers). An HTTP server listening on that port waits for a client's request message. Upon receiving the request, the server sends back a status line, such as "HTTP/1.1 200 OK", and a message of its own. The body of this message is typically the requested resource, although an error message or other information may also be returned.
HTTP defines methods (sometimes referred to as verbs) to indicate the desired action to be performed on the identified resource. What this resource represents, whether pre-existing data or data that is generated dynamically, depends on the implementation of the server. Often, the resource corresponds to a file or the output of an executable residing on the server.
The HTTP/1.0 specification:section 8 defined the GET, POST and HEAD methods and the HTTP/1.1 specification:section 9 added 5 new methods: OPTIONS, PUT, DELETE, TRACE and CONNECT. By being specified in these documents their semantics are well known and can be depended upon. Any client can use any method and the server can be configured to support any combination of methods. If a method is unknown to an intermediate it will be treated as an unsafe and non-idempotent method. There is no limit to the number of methods that can be defined and this allows for future methods to be specified without breaking existing infrastructure. For example WebDAV defined 7 new methods and RFC5789 specified the PATCH method.
HTTP servers are required to implement at least the GET and HEAD methods and, whenever possible, also the OPTIONS method.][
Some methods (for example, HEAD, GET, OPTIONS and TRACE) are defined as safe, which means they are intended only for information retrieval and should not change the state of the server. In other words, they should not have side effects, beyond relatively harmless effects such as logging, caching, the serving of banner advertisements or incrementing a web counter. Making arbitrary GET requests without regard to the context of the application's state should therefore be considered safe.
By contrast, methods such as POST, PUT and DELETE are intended for actions that may cause side effects either on the server, or external side effects such as financial transactions or transmission of email. Such methods are therefore not usually used by conforming web robots or web crawlers; some that do not conform tend to make requests without regard to context or consequences.
Despite the prescribed safety of GET requests, in practice their handling by the server is not technically limited in any way. Therefore, careless or deliberate programming can cause non-trivial changes on the server. This is discouraged, because it can cause problems for Web caching, search engines and other automated agents, which can make unintended changes on the server.
Methods PUT and DELETE are defined to be idempotent, meaning that multiple identical requests should have the same effect as a single request (Note that idempotence refers to the state of the system after the request has completed, so while the action the server takes (e.g. deleting a record) or the response code it returns may be different on subsequent requests, the system state will be the same every time). Methods GET, HEAD, OPTIONS and TRACE, being prescribed as safe, should also be idempotent, as HTTP is a stateless protocol.
In contrast, the POST method is not necessarily idempotent, and therefore sending an identical POST request multiple times may further affect state or cause further side effects (such as financial transactions). In some cases this may be desirable, but in other cases this could be due to an accident, such as when a user does not realize that their action will result in sending another request, or they did not receive adequate feedback that their first request was successful. While web browsers may show alert dialog boxes to warn users in some cases where reloading a page may re-submit a POST request, it is generally up to the web application to handle cases where a POST request should not be submitted more than once.
Note that whether a method is idempotent is not enforced by the protocol or web server. It is perfectly possible to write a web application in which (for example) a database insert or other non-idempotent action is triggered by a GET or other request. Ignoring this recommendation, however, may result in undesirable consequences, if a user agent assumes that repeating the same request is safe when it isn't.
Implementing methods such as TRACE, TRACK and DEBUG is considered potentially insecure by some security professionals because attackers can use them to gather information or bypass security controls during attacks. Security software tools such as Tenable Nessus and Microsoft UrlScan Security Tool report on the presence of these methods as being security issues.
TRACK and DEBUG are not valid http 1.1 verbs in any event.
In HTTP/1.0 and since, the first line of the HTTP response is called the status line and includes a numeric status code (such as "404") and a textual reason phrase (such as "Not Found"). The way the user agent handles the response primarily depends on the code and secondarily on the response headers. Custom status codes can be used since, if the user agent encounters a code it does not recognize, it can use the first digit of the code to determine the general class of the response.
Also, the standard reason phrases are only recommendations and can be replaced with "local equivalents" at the web developer's discretion. If the status code indicated a problem, the user agent might display the reason phrase to the user to provide further information about the nature of the problem. The standard also allows the user agent to attempt to interpret the reason phrase, though this might be unwise since the standard explicitly specifies that status codes are machine-readable and reason phrases are human-readable.
In HTTP/0.9 and 1.0, the connection is closed after a single request/response pair. In HTTP/1.1 a keep-alive-mechanism was introduced, where a connection could be reused for more than one request. Such persistent connections reduce request latency perceptibly, because the client does not need to re-negotiate the TCP connection after the first request has been sent. Another positive side effect is that in general the connection becomes faster with time due to TCP's slow-start-mechanism.
Version 1.1 of the protocol also made bandwidth optimization improvements to HTTP/1.0. For example, HTTP/1.1 introduced chunked transfer encoding to allow content on persistent connections to be streamed rather than buffered. HTTP pipelining further reduces lag time, allowing clients to send multiple requests before waiting for each response. Another improvement to the protocol was byte serving, where a server transmits just the portion of a resource explicitly requested by a client.
HTTP is a stateless protocol. A stateless protocol does not require the HTTP server to retain information or status about each user for the duration of multiple requests. However, some web applications implement states or server side sessions using one or more of the following methods:
The most popular way of establishing an encrypted HTTP connection is HTTP Secure.
Two other methods for establishing an encrypted HTTP connection also exist, called Secure Hypertext Transfer Protocol and the HTTP/1.1 Upgrade header. Browser support, for these latter two, is, however, nearly non-existent,][ so HTTP Secure is the dominant method of establishing an encrypted HTTP connection.
The request message consists of the following:
The request line and headers must all end with <CR><LF> (that is, a carriage return character followed by a line feed character). The empty line must consist of only <CR><LF> and no other whitespace. In the HTTP/1.1 protocol, all headers except Host are optional.
A request line containing only the path name is accepted by servers to maintain compatibility with HTTP clients before the HTTP/1.0 specification in RFC 1945.
The response message consists of the following:
The Status-Line and headers must all end with <CR><LF> (a carriage return followed by a line feed). The empty line must consist of only <CR><LF> and no other whitespace.
Below is a sample conversation between an HTTP client and an HTTP server running on www.example.com, port 80.
A client request (consisting in this case of the request line and only one header) is followed by a blank line, so that the request ends with a double newline, each in the form of a carriage return followed by a line feed. The "Host" header distinguishes between various DNS names sharing a single IP address, allowing name-based virtual hosting. While optional in HTTP/1.0, it is mandatory in HTTP/1.1.
The ETag (entity tag) header is used to determine if a cached version of the requested resource is identical to the current version of the resource on the server. Content-Type specifies the Internet media type of the data conveyed by the HTTP message, while Content-Length indicates its length in bytes. The HTTP/1.1 webserver publishes its ability to respond to requests for certain byte ranges of the document by setting the header Accept-Ranges: bytes. This is useful, if the client needs to have only certain portions of a resource sent by the server, which is called byte serving. When Connection: close is sent in a header, it means that the web server will close the TCP connection immediately after the transfer of this response.
Most of the header lines are optional. When Content-Length is missing the length is determined in other ways. Chunked transfer encoding uses a chunk size of 0 to mark the end of the content. Identity encoding without Content-Length reads content until the socket is closed.
A Content-Encoding like gzip can be used to compress the transmitted data.
Historically, Gopher existed as a competitor to HTTP.
Telephone phobia (telephonophobia, telephobia) is reluctance or fear of making or taking phone calls, literally, "fear of telephone". Telephone phobia is also considered to be a type of social phobia or social anxiety problem. It is often compared to the fear of public speaking, in that both require engaging with an audience to a certain extent, followed by the fear of being criticized,judged or made a fool of.
As is common with various fears and phobias, there is a wide spectrum of severity of the fear of phone conversations and the corresponding difficulties. In 1993 it was reported that about 2.5 million people in Great Britain have telephone phobia.
The term Telephone Apprehension refers to a lower degree of telephone phobia, where it is the anxiety derived from telephones, but less severe than that of an actual phobia.
These people may have no problem communicating face to face, but have difficulty doing so over the telephone.
The fear of telephones can range from the action or thought of answering and receiving calls to the actual ringing produced by the telephone. The ringing sound can generate a string of anxieties, characterized by thoughts associated with having to speak, perform and converse. Many of those suffering from this phobia may perceive the other end as threatening or intimidating, or may worry about finding an appropriate time to call, in fear of being a nuisance. Another source of anxiety comes from the lack of body language, which no longer becomes available through the telephone and results in the individual losing their sense of control. Past experiences, such as overhearing something traumatic or an unpleasant and angry call, may also play a part in creating fear. Sufferers typically report fear that they would fail to respond appropriately in a telephone conversation, and fear finding nothing to say, which would end in embarrassing silence, stammering, or stuttering. The associated avoidance behavior includes asking others (e.g. relatives at home) to take their phone calls and exclusive use of answering machines.
Another reason is the sufferers may believe that people who call them bear bad or upsetting news, or that the person on the other end may be a prank caller.
A variety of symptoms can be seen in someone suffering from telephone phobia, many which are shared with anxiety. Some symptoms include nervous stomach, sweaty palms, rapid heartbeat, shortness of breath, nausea, dry mouth and trembling. The sufferer may experience feelings of panic, terror and dread. Resulting panic attacks can include hyperventilation and stress. These negative and agitating symptoms can be produced by both the mere thought of making and receiving calls and the action of doing so.
The telephone is important for both contacting others and accessing important and useful services. As a result, this phobia causes a great deal of stress and impacts peoples' personal lives, work lives and social lives. As a result, the sufferers avoid many activities, such as scheduling events or clarifying information. Strain is created in the workplace specifically because work with telephones may play a crucial role within the career.
Phobias of this sort can usually be treated by different types of therapies, including: cognitive behavioral therapy (CBT), psychotherapy, behavior therapy and exposure therapy. Other suggested actions consist of planning the conversation ahead of time and rehearsing, writing or noting down what needs to be said.
Practice also plays an important factor in overcoming fear. It is helpful to the sufferers to increase phone usage at a slow pace, starting with simple calls and gradually working their way up. For example, starting with automated calls, moving to family and friends and then further extending the length of the conversations and with whom the conversations are being held.
List of HTTP status codes
MOBILedit Forensic is digital forensics product by Compelson Labs that searches, examines and report datas from GSM/CDMA/PCS cell phone devices. MOBILedit! connects to cell phone devices via an Infrared (IR) port, a Bluetooth link, Wi-Fi, or a cable interface. After connectivity has been established, the phone model is identified by its manufacturer, model number, and serial number (IMEI) and with a corresponding picture of the phone.
Data acquired from cell phone devices are stored in the .med file format. After a successful logical acquisition, the following fields are populated with data: subscriber information, device specifics, Phonebook, SIM Phonebook, Missed Calls, Last Numbers Dialed, Received Calls, Inbox, Sent Items, Drafts, Files folder. Items present in the Files folder, ranging from Graphics files to Camera Photos and Tones, depend on the phone’s capabilities. Additional features include the myPhoneSafe.com service, which provides access to the IMEI database to register and check for stolen phones.
MOBILedit is a platform that works with a variety of phones and smartphones (a complete list of supported handsets is available on the manufacturer’s website) and explores contents of the phone through a MS Outlook-like folder structure. This allows backup of the information stored on the phone, storing it on a PC or copy data to another phone via Phone Copier feature.
The following is a list of Hypertext Transfer Protocol (HTTP) response status codes. This includes codes from IETF internet standards as well as other IETF RFCs, other specifications and some additional commonly used codes. The first digit of the status code specifies one of five classes of response; the bare minimum for an HTTP client is that it recognises these five classes. The phrases used are the standard examples, but any human-readable alternative can be provided. Unless otherwise stated, the status code is part of the HTTP/1.1 standard (RFC 2616).
The Internet Assigned Numbers Authority (IANA) maintains the official registry of HTTP status codes.
Microsoft IIS sometimes uses additional decimal sub-codes to provide more specific information, but these are not listed here.
Request received, continuing process.
This class of status code indicates a provisional response, consisting only of the Status-Line and optional headers, and is terminated by an empty line. Since HTTP/1.0 did not define any 1xx status codes, servers must not send a 1xx response to an HTTP/1.0 client except under experimental conditions.
This class of status codes indicates the action requested by the client was received, understood, accepted and processed successfully.
The client must take additional action to complete the request.
This class of status code indicates that further action needs to be taken by the user agent to fulfil the request. The action required may be carried out by the user agent without interaction with the user if and only if the method used in the second request is GET or HEAD. A user agent should not automatically redirect a request more than five times, since such redirections usually indicate an infinite loop.
The 4xx class of status code is intended for cases in which the client seems to have erred. Except when responding to a HEAD request, the server should include an entity containing an explanation of the error situation, and whether it is a temporary or permanent condition. These status codes are applicable to any request method. User agents should display any included entity to the user.
The server failed to fulfill an apparently valid request.
Response status codes beginning with the digit "5" indicate cases in which the server is aware that it has encountered an error or is otherwise incapable of performing the request. Except when responding to a HEAD request, the server should include an entity containing an explanation of the error situation, and indicate whether it is a temporary or permanent condition. Likewise, user agents should display any included entity to the user. These response codes are applicable to any request method.
4-1-1 is the telephone number for local directory assistance in the United States and Canada. One exception is the Pacific Northwest, which used 1-1-3 until the mid-1980s. Until the early 1980s, 4-1-1 calls were free in most states.
4-1-1 has also been used for long-distance directory assistance in most areas in the United States and all of Canada. The traditional long-distance directory assistance number is 1-area code-555-1212.
4-1-1 is also commonly referred to as "D.A.", "Directory Assistance", or "Information". Prior to the introduction of Direct Distance Dialing (DDD) in the 1950s, which required dialing "1" to initiate a DDD call, the number for "Information" was 1-1-3 ("Repair" was 1-1-4). All existing local numbers beginning with 1 had to be changed, so "Information" and "Repair" (and others) changed to 411 and 611, respectively. Approximately 6 billion calls are made to 4-1-1 within the United States every year.
Outside North America, "1-1-N" numbers are still in use, for these and other services. In most European countries "1-1-N" numbers are related to emergency services and 112 is the European Unified Emergency Number.
The services of directory assistance queries is often outsourced to a call centre who specializes in that function. Historically, when a single carrier provided most of the telephony services for a region, the data used to satisfy the search could exclusively come for that carriers subscriber rolls. Today, when the market is fragmented amongst many carriers, the data must be aggregated by a data aggregator specializing in directory listings, such as LSSi. The data aggregator distributes the data to the 4-1-1 services either on a “live” basis, actually servicing each query, or by periodically transferring large swaths of listings to the call center's systems for local searching.
The data aggregator collects the data from the rolls of many telecommunication carriers. Some carriers such as Vonage do not send their customer rolls to the aggregator. Their customers can get their listings in the directory assiatance database using a free service such as ListYourself.net.
4-1-1 landline service has been historically provided by local telephone companies, including those of the former Bell System or subsequent Regional Bell Operating Companies (RBOCs). Telephone carriers since that time may provide the 4-1-1 calls to the customer free of charge and use ad supported or a customer retention model
Since the 1984 Bell System divestiture, the RBOCs in the United States have priced 4-1-1 use higher to an average of $1.25 USD per call, compared to $0.50 CAD in most of Canada,][ providing opportunities for competing services in the United States, such as ad-sponsored 1-800-FREE-411.
In addition to the local and long distance directory services, there is also consumer-choice and privacy-protected "Wireless 411 Service". As specified by the industry, the service will give consumers the choice of including their wireless phone numbers in voice 411. Consumers who choose to opt in will not have their information disclosed for print, online directories, lists, or telemarketing firms. The service will allow any landline or wireless phone user to call 4-1-1 and be connected to the wireless listing of a person who has chosen to participate in the service. Carriers who make up the industry LLC creating the service include Alltel (now absorbed by Verizon Wireless), AT&T, Sprint Nextel and T-Mobile.
In computing, a user agent is software (a software agent) that is acting on behalf of a user. For example, an email reader is a Mail User Agent, and in the Session Initiation Protocol (SIP), the term user agent refers to both end points of a communications session.
In many cases, a user agent acts as a client in a network protocol used in communications within a client–server distributed computing system. In particular, the Hypertext Transfer Protocol (HTTP) identifies the client software originating the request, using a "User-Agent" header, even when the client is not operated by a user. The SIP protocol (based on HTTP) followed this usage.
When a software agent operates in a network protocol, it often identifies itself, its application type, operating system, software vendor, or software revision, by submitting a characteristic identification string to its operating peer. In HTTP, SIP, and SMTP/NNTP protocols, this identification is transmitted in a header field User-Agent. Bots, such as Web crawlers, often also include a URL and/or e-mail address so that the Webmaster can contact the operator of the bot.
In HTTP, the User-Agent string is often used for content negotiation, where the origin server selects suitable content or operating parameters for the response. For example, the User-Agent string might be used by a web server to choose variants based on the known capabilities of a particular version of client software.
The User-Agent string is one of the criteria by which Web crawlers may be excluded from accessing certain parts of a Web site using the Robots Exclusion Standard (robots.txt file).
As with many other HTTP request headers, the information in the "User-Agent" string contributes to the information that the client sends to the server, since the string can vary considerably from user to user.
The User-Agent string format is currently specified by Section 14.43 of RFC 2616 (HTTP/1.1) The format of the User-Agent string in HTTP is a list of product tokens (keywords) with optional comments. For example if your product were called WikiBrowser, your user agent string might be WikiBrowser/1.0 Gecko/1.0. The "most important" product component is listed first. The parts of this string are as follows:
During the first browser war, many web servers were configured to only send web pages that required advanced features to clients that were identified as some version of Mozilla.][ Other browsers were considered to be older products such as Mosaic, Cello or Samba and would be sent a bare bones HTML document.
For this reason, most Web browsers use a User-Agent value as follows: Mozilla/[version] ([system and browser information]) [platform] ([platform details]) [extensions]. For example, Safari on the iPad has used the following:
The components of this string are as follows:
The popularity of various Web browser products has varied throughout the Web's history, and this has influenced the design of Web sites in such a way that Web sites are sometimes designed to work well only with particular browsers, rather than according to uniform standards by the World Wide Web Consortium (W3C) or the Internet Engineering Task Force (IETF). Web sites often include code to detect browser version to adjust the page design sent according to the user agent string received. This may mean that less-popular browsers are not sent complex content (even though they might be able to deal with it correctly) or, in extreme cases, refused all content. Thus, various browsers have a feature to cloak or spoof their identification to force certain server-side content. For example, the Android browser identifies itself as Safari (among other things) in order to aid compatibility.
Other HTTP client programs, like download managers and offline browsers, often have the ability to change the user agent string.
Spam bots and Web scrapers often use fake user agents.
At times it has been popular among Web developers to initiate Viewable With Any Browser campaigns, encouraging developers to design Web pages that work equally well with any browser.
A result of user agent spoofing may be that collected statistics of Web browser usage are inaccurate.
The term user agent sniffing refers to the practice of Web sites showing different content when viewed with a certain user agent. On the Internet, this will result in a different site being shown when browsing the page with a specific browser. A useful example of this is Microsoft Exchange Server 2003's Outlook Web Access feature. When viewed with Internet Explorer 6 (or newer), more functionality is displayed compared to the same page in any older browsers, because older browsers could not render the same content.][ User agent sniffing is mostly considered poor practice, since it encourages browser-specific design and penalizes new browsers with unrecognized user agent identifications. Instead, the W3C recommends creating HTML markup that is standard, allowing correct rendering in as many browsers as possible, and to test for specific browser features rather than particular browser versions or brands.
Web sites specifically targeted towards mobile phones, like NTT DoCoMo's I-Mode or Vodafone's Vodafone Live! portals, often rely heavily on user agent sniffing, since mobile browsers often differ greatly from each other. Many developments in mobile browsing have been made in the last few years,][ while many older phones that do not possess these new technologies are still heavily used. Therefore, mobile Web portals will often generate completely different markup code depending on the mobile phone used to browse them. These differences can be small, e.g., resizing of certain images to fit smaller screens, or quite extensive, e.g., rendering of the page in WML instead of XHTML.
Web browsers created in the United States, such as Netscape Navigator and Internet Explorer, use the letters U, I, and N to specify the encryption strength in the user agent string. Until 1996, when the United States government disallowed encryption with keys longer than 40 bits to be exported, vendors shipped various browser versions with different encryption strengths. "U" stands for "USA" (for the version with 128-bit encryption), "I" stands for "International" — the browser has 40-bit encryption and can be used anywhere in the world — and "N" stands (de facto) for "None" (no encryption). Following the lifting of export restrictions, most vendors supported 256-bit encryption.