Definition
Caching is the practice of storing a copy of data in a temporary location so it can be retrieved faster the next time it is needed. Instead of generating the same web page from scratch for every visitor, or querying a database for the same information repeatedly, a cache keeps a ready-made copy. Caching happens at many levels — the browser caches images and files locally, servers cache processed pages, and databases cache frequent query results. Each layer reduces the work needed to fulfil a request.
Why It Matters
Without caching, every page view on your website requires the server to gather data, assemble the page, and send it to the visitor — even if the result is identical to what was sent a second ago. This wastes processing power and slows down the experience for everyone. Caching dramatically reduces server load and page load times, which directly improves user experience and search engine rankings. For content that does not change frequently — your about page, product descriptions, blog posts — caching means the server does the heavy work once and serves the result thousands of times. This is one of the simplest and most effective performance optimisations available.
Example
A news website publishes articles that get thousands of views per hour. Without caching, every visitor triggers a database query and page assembly process. The server struggles under the load and pages take several seconds to appear. After implementing page caching, the first visitor triggers the build, and every subsequent visitor receives the cached version instantly. The server load drops by over ninety percent, pages load in under a second, and the site handles traffic spikes without slowing down.