Caching is the process of storing frequently used data on the server to fulfill subsequent requests.You will discover that grabbing data or objects from memory is much faster than recreating the web pages or items contained in them from scratch. A Proper use and fine tune of caching approach of caching will result on better performance and scalability of your site. However improper use of caching will actually slow down and consume lots of your server performance and memory usage. Good candidate to use caching is if you have infrequent chance of data or static content of web page.