What is a cache

Caching (pronounced “cashing”) is the process of storing data in a cache. The cache is a collection of temporarily stored data for quick access upon request. In computers, information is usually stored on a hard disk.

A cache can reside on your computer or on a website. For example, the files you automatically request by looking at a Web page are stored on your hard disk in a cache subdirectory under the directory for your browser. When you return to a page you’ve recently looked at, the browser can get those files from the cache rather than the original server, saving you time and saving the network the burden of additional traffic. When it is requested, a computer needs to run several processes before the information can be presented.

Caching solves this issue by processing the frequently requested information and then storing it in temporary storage or memory. This allows computers to access the file quickly.

WordPress caching can be implemented as a plugin or with subscriptions to online caching services.

Source: https://whatis.techtarget.com/definition/caching