Online chat may refer to any kind of communication over the Internet that offers a real-time transmission of text messages from sender to receiver. Chat messages are generally short in order to enable other participants to respond quickly. Thereby, a feeling similar to a spoken conversation is created, which distinguishes chatting from other text-based online communication forms such as Internet forums and email. Online chat may address point-to-point communications as well as multicast communications from one sender to many receivers and voice and video chat, or may be a feature of a web conferencing service.
Online chat in a less stringent definition may be primarily any direct text-based or video-based (webcams), one-on-one chat or one-to-many group chat (formally also known as synchronous conferencing), using tools such as instant messengers, Internet Relay Chat (IRC), talkers and possibly MUDs. The expression online chat comes from the word chat which means "informal conversation". Online chat includes web-based applications that allow communication –often directly addressed, but anonymous between users in a multi-user environment. Web conferencing is a more specific online service, that is often sold as a service, hosted on a web server controlled by the vendor.
Text messaging, or texting, is the act of typing and sending a brief, electronic message between two or more mobile phones or fixed or portable devices over a phone network. The term originally referred to messages sent using the Short Message Service (SMS); it has grown to include messages containing image, video, and sound content (known as MMS messages). The sender of a text message is known as a texter, while the service itself has different colloquialisms depending on the region. It may simply be referred to as a text in North America, the United Kingdom, Australia, New Zealand and the Philippines, an SMS in most of mainland Europe, and a TMS or SMS in the Middle East, Africa and Asia.
Text messages can be used to interact with automated systems to, for example, order products or services, or participate in contests. Advertisers and service providers use direct text marketing to message mobile phone users about promotions, payment due dates, etcetera instead of using mail, e-mail or voicemail.