What is JDBC Connection Pooling... ?

Can any one explain whta is JDBC Connection Pooling.. when, where and why used ?
[87 byte] By [Shebua] at [2007-11-27 9:59:13]
# 1
Connecting to the DB is expensive (in terms of time). Connection pooling gives you the ability to reuse a set of connections without creating new connections everytime. It might be obvious that this gives very positive results in terms of DB performance.
BalusCa at 2007-7-13 0:30:16 > top of Java-index,Database Connectivity,Java Database Connectivity (JDBC)...