Caching
Storing copies of data or computed results temporarily so future requests for the same data can be served faster.
Definition
Caching is the practice of saving a copy of data – a web page, a database query result, an API response – in a faster storage layer so that subsequent requests can be fulfilled without repeating expensive work. Caches exist at many levels: browser, CDN, server, and database.
Why it matters
Generating a page dynamically – fetching records from a database, running logic, rendering HTML – takes time and server resources. If that page looks the same for every visitor, generating it 10,000 times is wasteful. Caching lets you do the work once and reuse the result, dramatically improving performance and reducing infrastructure costs.
Example
Your browser caches images and scripts so revisiting a site is faster than the first visit. WordPress plugins like WP Rocket cache rendered HTML. Redis and Memcached are used server-side to cache database query results. When a site says “please clear your cache,” they mean a stale copy is causing you to see outdated content.