[[File:cache,basic.svg|thumb|upright=1|Diagram of a CPU memory cache operation]]
In [[computing]], a '''cache''' ({{IPAc-en|audio=LL-Q1860 (eng)-Back ache-cache.wav|k|æ|ʃ}} {{respell|KASH}})<ref>
{{cite web|url=http://www.oxforddictionaries.com/definition/english/cache|archive-url=https://web.archive.org/web/20120818122040/http://oxforddictionaries.com/definition/english/cache|url-status=dead|archive-date=18 August 2012|title=Cache|work=Oxford Dictionaries|access-date=2 August 2016}}</ref> is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. A '''cache hit''' occurs when the requested data can be found in a cache, while a '''cache miss''' occurs when it cannot. Cache hits are served by reading data from the cache, which is faster than recomputing a result or reading from a slower data store; thus, the more requests that can be served from the cache, the faster the system performs.<ref>{{Cite journal|last1=Zhong|first1=Liang|last2=Zheng|first2=Xueqian|last3=Liu|first3=Yong|last4=Wang|first4=Mengting|last5=Cao|first5=Yang|date=February 2020|title=Cache hit ratio maximization in device-to-device communications overlaying cellular networks|url=http://dx.doi.org/10.23919/jcc.2020.02.018|journal=China Communications|volume=17|issue=2|pages=232–238|doi=10.23919/jcc.2020.02.018|s2cid=212649328|issn=1673-5447}}</ref>
To be cost-effective, caches must be relatively small. Nevertheless, caches are effective in many areas of computing because typical [[Application software|computer applications]] access data with a high degree of [[locality of reference]]. Such access patterns exhibit temporal locality, where data is requested that has been recently requested, and spatial locality, where data is requested that is stored near data that has already been requested.
