Omnitrans is the only way to get around for most people here. If you don't have a car, it's your only hope. The routes pass near the industrious areas but sometimes not close enough so expect to have to walk a decent distance to get where you got to go. There are discounts for seniors, students and children. Go to Omnitrans.org for more details.
Metrolink (metrolinktrains.com) is the local commuter train for the Inland Empire area. It has lines that cover most of the southwest corner of the state and stops in all the major counties/cities. Amtrak is another type of train. They go everywhere, in and out of state.