Caching — PlanetScale

Caching is a fundamental computing concept that improves performance by storing frequently accessed data in faster, smaller storage layers. The article explores caching principles from CPU cache layers to database buffer pools, covering hit rates, temporal and spatial locality, replacement policies like LRU and LIFO, and real-world applications including CDNs and social media platforms. It demonstrates how caching works across different scales, from individual computers to global distributed systems, emphasizing the trade-offs between speed, capacity, and cost.