A means of identifying a user or individual session in computer networks and applications. A distinction is made between software and hardware tokens.

A software token usually consists of an encrypted sequence of characters that accurately identifies the object and determines the level of privileges. It is generated by an authorization system and linked to a specific session, network client, or data packet.

A hardware token is a device on which a unique password is stored or able to be generated according to certain rules. For authentication, hardware tokens can be physically connected to the computer via a communications port or special reader. The simplest hardware tokens simply output a unique password for the current session on a built-in display.