why use c3p0.jar

I used jdbc in normal way.

like below,
 Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn =  DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:ORA92", "scott", "tiger");


but when I read c3p0.jar manual , they use DataSource way and xml.

What is different and benefit to use??

Tell me advice.