A cache stores recently-used information in a place where it can be accessed extremely fast. For example, a Web browser like Internet Explorer uses a cache to store the pages, images, and URLs of recently visted Web sites on your hard drive. With this neat strategy, when you visit a page you have recently been to, the pages and images don't have to be downloaded to your computer all over again. Because accessing your computer's hard disk is much faster than accessing the Internet, caching Web sites can speed up Web browsing significantly. Most Web browsers allow you to adjust the size of the cache in in browser preferenecs.
There are many different types of caches but they all serve the same purpose.Another common type of cache is a disk cache. This stores information you have recently read from your hard disk in the computer's RAM, or memory. Since accessing RAM is much faster than reading data off the hard disk, this can help you access common files and folders on your hard drive much faster.
Another type of cache is a processor cache which stores small amounts of information right next to the processor. This helps make the processing of common instructions much more efficient, thereby speeding up computation time.