Here is the link which gives overview about custom settings https://help.salesforce.com/apex/HTViewHelpDoc?id=cs_about.htm I strongly recommend you to do some research on your question before post it in forum, the question which you asked can be found in google. Make use of developer forum effectively.
I strongly recommend you to do some research on your question before post it in forum, the question which you asked can be found in google. Make use of developer forum effectively.