From CSGSA

The two major mass transit operators in the Berkeley area are AC Transit bus service and the BART rapid-transit train system that covers most of the bay area. Across the bay, San Francisco has its own bus and light-rail system, the much-maligned Muni.

The MTC provides an integrated tool for planning trips via all the bay area's public transit providers, as does Google. There are also separate guides for BART and for AC Transit.

If you are a UC Berkeley student, you are eligible for the Class Pass, which lets you ride AC Transit and BearTransit (campus shuttle[1]) buses for free. Drop by the Cal 1 Card (ID card) office on Lower Sprowl Plaza to pick up the sticker. You'll need a new one at the beginning of each semester (the Spring semester one is also good for summer). For them to give it to you, you'll need to be officially registered according to [2]; this includes being enrolled in at least one class.

If you're trying to head to an airport, there are specific guides for getting to Oakland International and San Francisco International.

If you will be regularly commuting to (or in some cases, from) San Francisco consider AC Transit's Transbay lines, which (depending on which stops you use) can be faster than BART, sometimes have WiFi, and are free for Berkeley students. Some lines run all day in both directions; but most only go to SF in the morning and return in the afternoon.

Amtrak's capitol corridor line provides quick and reasonably priced service to Sacramento. The Berkeley Amtrak station is underneath University Ave at the freeway, and is accessible via AC Transit. You probably want to book tickets online, as they cannot be purchased at the station.

If you happen to travel back in time to the 1970's, you've still got options.