A cache is a hardware or software component that stores data so that future requests for that data can be served faster. Specifically, it refers to a mechanism for the temporary storage of web pages, images, and other types of data that allows for faster loading of internet content.
Web caches store copies of resources loaded from web servers, such as HTML pages, images, CSS and JavaScript files, and so on. The next time a user requests the same resource, it can be loaded from the cache, which is often located geographically closer to the user than the original server.
Caching allows for reduced latency and bandwidth usage. Browsers employ caches locally, while separate network caches can be implemented to speed up delivery across groups of users.
Managed effectively, caching improves website performance substantially.