For god sake Try googling b4 u post anything on the forums.
if u could have done that u cud have got the following links for reference.
http://forum.java.sun.com/thread.jspa?threadID=676137&messageID=3949294
http://www.sap-img.com/java/difference-between-servletcontext-and-servletconfig.htm
http://www.geekinterview.com/question_details/2409
http://www.jguru.com/faq/view.jsp?EID=339337
we can place the resources that are needed to shared by most of the components in a webapllication inside a servlet context object as it is unique for the entire webapplication.
where as we can place the resources that we need with in a specific servlet inside a servlet config object as it is unique for each servlet.
most of the times we use these objects to hold the information about the database connections, page attributes i.e., color etc