Static resources like css, js images etc. need not be reloaded from the server every time until and unless we want the old one needs to be replaced by the new one.
Sometimes we need to cache static resources so that performance of the site can be improved over the time.
Cache is defined as hardware or software feature that stores data in temporary storage space that permits quick access to stored data.
Web browsers like Chrome, Firefox, Internet Explorer etc. use the cache for regularly accessed web pages. This feature enables the browser to retrieve data from cache than from web page files.