Caching in PHP (Reduce DB Load and Speed Up Pages)

Caching means storing results so you don't recompute them every time. ## What to cache - expensive DB queries (top posts, homepage stats) - API responses (if they do not change quickly) - rendered HTML fragments (optional) ## Basic caching concept ```mermaid flowchart LR A[Request] --> B{Cache hit?} B -->|Yes| C[Return cached data] B -->|No| D[Compute / Query DB] D --> E[Store in cache] E --> C ``` ## Common cache systems - Redis (very popular) - Memcached - filesystem cache (small projects) ## Key idea Caching is powerful, but you must decide: - how long to cache (TTL) - when to invalidate cache (on updates) > Next: PHP performance tips, OPcache and practical tuning.