How Caching Cut a Product Page's Load Time from Three Seconds to Three Milliseconds

A product page that took three seconds to load dropped to three milliseconds after its developers added caching, with the same server, database and code. Caching works by storing a copy of frequently requested data closer to where it is needed, so repeated requests skip slow database queries. The common cache-aside pattern checks the cache first and falls back to the database on a miss, then stores the result with an expiry time. The article also warns that cached copies can go stale when source data changes, and recommends writing to the database first and then deleting the cache entry rather than updating it.