The Extensible Authentication Protocol (EAP) is a protocol for wireless networks that expands on authentication methods used by the Point-to-Point Protocol (PPP), a protocol often used when connecting a computer to the Internet. EAP can support multiple authentication mechanisms, such as token cards, smart cards, certificates, one-time passwords, and public key encryption authentication.
Here's how it works: in communications using EAP, a user requests connection to a wireless network through an access point (a station that transmits and receives data, sometimes known as a transceiver). The access point requests identification (ID) data from the user and transmits that data to an authentication server. The authentication server asks the access point for proof of the validity of the ID. After the access point obtains that verification from the user and sends it back to the authentication server, the user is connected to the network as requested.