A vehicle identification number, commonly abbreviated to VIN, is a unique code including a serial number, used by the automotive industry to identify individual motor vehicles, towed vehicles, motorcycles, scooters and mopeds as defined in ISO 3833.
VINs were first used in 1954. From 1954 to 1981, there was no accepted standard for these numbers, so different manufacturers used different formats.
A unique key or primary key is a key that uniquely defines the characteristics of each row. The primary key has to consist of characteristics that cannot collectively be duplicated by any other row.
In an entity relationship diagram of a data model, one or more unique keys may be declared for each data entity. Each unique key is composed from one or more data attributes of that data entity. The set of unique keys declared for a data entity is often referred to as the candidate keys for that data entity. From the set of candidate keys, a single unique key is selected and declared the primary key for that data entity. In an entity relationship diagram, each entity relationship uses a unique key, most often the primary key, of one data entity and copies the unique key data attributes to another data entity to which it relates. This inheritance of the unique key data attributes is referred to as a foreign key and is used to provide data access paths between data entities. Once the data model is instantiated into a database, each data entity usually becomes a database table, unique keys become unique indexes associated with their assigned database tables, and entity relationships become foreign key constraints. In integrated data models, commonality relationships do not become foreign key constraints since commonality relationships are a peer-to-peer type of relationship.
A key is a device that is used to operate a lock. A typical key is a small piece of metal consisting of two parts: the blade, which slides into the keyway of the lock and distinguishes between different keys, and the bow, which is left protruding so that torque can be applied by the user. A key is usually intended to operate one specific lock or a small number of locks that are keyed alike, so each lock requires a unique key. The key serves as a security token for access to the locked area; only persons having the correct key can open the lock and gain access.
Keys provide an inexpensive, though imperfect, method of access control for access to physical properties like buildings, vehicles and cupboards or cabinets. As such, keys are an essential feature of modern living, and are common around the globe. It is common for people to carry the set of keys they need for their daily activities around with them, often linked by a keyring adorned by trinkets usually known as a keychain.