CodeHS The Internet Practice Test

Caching in browsers means saving copies of resources locally so future requests can be served quickly without re-downloading. When you load a page, the browser fetches files like HTML, CSS, JavaScript, and images and may keep them in a local cache. On a subsequent visit (or revisiting the same page), the browser can reuse those cached files instead of downloading them again, which makes the page load faster and uses less network data. This behavior is controlled by headers and expiration rules, so resources can be refreshed when needed.

The other descriptions don’t fit caching: running code on the server is server-side processing, not browser caching; encrypting data is about protecting data in transit, not storing copies for speed; and allocating memory for scripts during page load refers to runtime memory management, not caching resources for faster future requests.