Explores cache implementation in Go APIs, covering fundamental concepts like cache hits/misses, eviction policies (LRU, LFU, FIFO), and invalidation strategies. Demonstrates building a native in-memory cache using Go maps with mutex protection and TTL expiration. Compares caching strategies including write-through and write-back patterns, showing practical code examples for a transaction history API. Discusses when caching becomes necessary based on database load indicators and performance metrics.