[[File:Clipper_card.jpg|thumb|right|300px|The Clipper Card is an automated fare medium used in the San Francisco Bay Area by seven of the region's transit agencies, including Bay Area Rapid Transit (BART). Photo by Flickr user sam_churchill.]]
Transit agencies have traditionally used cash fare systems, but cash is expensive to transport, count, and guard. It can also be inconvenient for riders to have to pay an exact fare for each leg of a trip. For these reasons, many agencies have introduced automated fare media by expanding fare payment to electronic, magnetic stripe contact cards and more recently to smart cards. A smart card is a contactless, reusable, prepaid card that includes an embedded microchip to monitor fare transactions and stored balance. Payment is processed through a microchip using [[near field communications]] or [[radio frequency identification (RFID)]]. Transit agencies view smart cards as a potentially revolutionary advancement due to their benefits, which include convenience, greater fare flexibility, operational cost savings, service enhancements, decreased fare processing time, centralized fare collection, more efficient fare pricing, and greater capacity for data compilation of ridership and travel behavior.
==Types of Systems==