What is Caching? — UK Software Development Guide

4 min readJune 2025ClickMasters Technical TeamReviewed by James Whitmore, CTO
what is caching in software

Direct Answer

Caching is the practice of storing copies of data in a fast-access storage location (the cache) so future requests for that data can be served faster. Instead of performing expensive database queries or API calls every time, cached data is returned immediately from memory. Common caching tools: Redis (in-memory), Memcached, CDN edge caching, browser caching.

Caching in the UK

Caching has UK GDPR implications. Caches can contain personal data — and must be treated as such. Redis caches storing session data or user profiles must: have appropriate TTL (time to live) aligned with your data retention policy, be invalidated when personal data is deleted (right to erasure must clear cached data as well as primary database records), and be secured against unauthorised access (Redis should never be exposed publicly without authentication). CDN caches must never contain personal data — see CDN entry for UK GDPR data residency implications.

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