A contactless smart card is any pocket-sized card with embedded integrated circuits that can process and store data, and communicate with a terminal via radio waves. There are two broad categories of contactless smart cards. Memory cards contain non-volatile memory storage components, and perhaps some specific security logic. Contactless smart cards can be used for identification, authentication, and data storage. They also provide a means of effecting business transactions in a flexible, secure, standard way with minimal human intervention.
Contactless smart card readers use radio waves to communicate with, and both read and write data on a smart card. When used for electronic payment, they are commonly located near PIN pads, cash registers and other places of payment. When the readers are used for public transit they are commonly located on fare boxes, ticket machines, turnstiles, and station platforms as a standalone unit. When used for security, readers are usually located to the side of an entry door.