What is Caching?

Caching stores frequently accessed data in fast storage so you don't have to recompute or re-fetch it. It's like keeping your most-used tools on your desk instead of in the garage — much faster to grab when you need them.

How It Works:

1. First request: Compute/fetch data (slow)
2. Store result in cache (fast storage)
3. Next request: Return cached data (very fast!)
4. Cache expires or gets invalidated
5. Repeat

Types of Caches:

• Browser cache: Stores web assets locally
• CDN cache: Content delivery networks cache globally
• Application cache: In-memory cache (Redis, Memcached)
• Database cache: Query result caching
• CPU cache: Hardware-level speed boost

Cache Strategies:

• Cache-aside: App checks cache, fetches if miss
• Write-through: Write to cache and database simultaneously
• Write-back: Write to cache, sync to database later

Benefits:

• Speed: Much faster than recomputing
• Reduced load: Less work for databases/servers
• Better UX: Faster response times

FAQ

What should I cache?

Frequently accessed, expensive to compute, and relatively static data. Don't cache user-specific, frequently changing, or sensitive data without care.

What's cache invalidation?

Removing or updating cached data when the source data changes. It's one of the hard problems in computer science!