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

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.