Caching

Storing the result of an expensive operation (database query, API call, computation) so it can be served instantly next time without re-running the original operation.

Caching makes apps dramatically faster and cheaper to run at scale. Without it, every page load hits the database; with it, popular pages serve thousands of users from memory.

A founder's public course catalogue is cached, the database is queried once, the result is stored, and every visitor gets it instantly. The cache refreshes every 10 minutes.