Michael San Francisco also has a public transportation system called the "San Francisco Municipal Railway," or "MUNI" for short. Bus lines with numbers and streetcars with letters (J, K, L, M, N) transport people above ground. The line that passes by our house on Church Street is called J-Church. By the way, there is a fairly well-known alternative rock band in the USA named "J-Church." The music might be rather ungrounded, but guess which city they come from?
There's also a subway: the so-called 'BART', which stands for "Bay Area Rapid Transit". However, one shouldn't imagine it as a subway network like those in European metropolises. Instead, there is exactly one line from Daly City (south of San Francisco) up to the Bay Bridge, to continue under the Bay. On the other side (in the East Bay), it continues in various directions. While BART is much more reliable than the MUNI, it still doesn't run as regularly as its European counterparts: on weekdays during the day, it might run every 10 minutes, but on Sundays and public holidays, you might end up waiting around at the subway station for 20 minutes and more.