Caltrain is a form of public transportation that links San Francisco, the peninsula, San Jose, Gilroy, and everything in between. Caltrain is inconvenient because trains only run about once an hour, except during rush hour. Plans were made in 1996 to connect Caltrain to BART, but the project has been delayed numerous times. To get to downtown San Francisco from Caltrain, you must take MUNI.
Caltrain now runs Baby Bullet trains on weekdays, so it is great for commuters. The new bullet train cars are much more comfortable than the old ones. Caltrain is now a pleasant ride.