what is car pool?

Here is the definition for car pool: a group of associated people sharing the use of their cars, each in turn driving the others
- shared driving arrangements: the actual arrangement made by a group of people such as coworkers or parents to share the duty of driving to and from somewhere.

Carpooling is a flexible and convenient way to get where you need to go, and if you commute over Bay Area bridges, you can cross toll-free. Carpool as many days as you want, one-way or roundtrip. All you need is one or two other people to make it work. Carpool with neighbors, coworkers, family, friends from the gym, or sign up FREE with the 511 RideMatch Service to instantly find other people who live and work nearby to share commutes.

you may get all your questions answer by visiting 511.org
(Bay Area Bridges are in California, USA.)

I'm NOT sure if Asia has such service though.