A cache is a tem­po­rary stor­age area for instruc­tions and data, usu­ally imple­mented in high-speed mem­ory. It is used to shorten data access times, reduce latency and improve input/out­put oper­a­tions.

Because almost all appli­ca­tion work­load depends upon input/out­put oper­a­tions, caching data improves appli­ca­tion per­for­mance. It repli­cates infor­ma­tion from slower stor­age or net­work resources to enable quicker access while using fewer resources than the orig­i­nal source.

For exam­ple, Web browsers such as Chrome, Fire­fox, Inter­net Explorer, Edge or Safari use browser caches to improve per­for­mance for fre­quently accessed web­pages. While vis­it­ing a web­page, the files requested by the browser are stored locally in the browser cache. When re-vis­it­ing the page, most of the files can be retrieved from this cache instead of hav­ing to down­load them again. This is much faster and allows for a bet­ter user expe­ri­ence.