A cache is a hardware or software component that stores data so that future requests for that data can be served more quickly. The data stored in a cache can be the result of a previous computation or the duplicates of data stored elsewhere. Caches are used to improve the performance of a system by reducing the time it takes to access data and the average time it takes to access data.

There are different types of caches, such as processor caches, web browser caches and application caches. Processor caches are used to store data that is frequently accessed by the CPU so that it can be accessed more quickly. Web browser caches store web page data such as HTML, CSS and JavaScript so that the browser does not have to re-download these resources every time the user visits a web page. Application caches are used to store data that is frequently used by an application, such as images, audio files and other resources, so that the application does not have to retrieve these resources every time they are needed.