The San Francisco Commuting System is a rapid transit system that serves the San Francisco Bay Area. It is commonly referred to as BART, which stands for Bay Area Rapid Transit. BART is a four-letter acronym that is used to refer to the system, which consists of six lines and 45 stations. The system connects the cities of San Francisco, Oakland, Berkeley, Fremont, and other cities in the Bay Area. BART provides a convenient and efficient way for commuters to travel throughout the region.