What it is and the problem it solves
Memcached is a general-purpose distributed memory-caching system. It solves the problem of repeated, expensive reads from databases or APIs in dynamic websites.
How it works
Memcached runs as a client–server daemon that provides a hash table distributed across multiple machines. It stores data in RAM. When full, it evicts older entries using LRU order. It depends on libevent for asynchronous I/O.
What works
Its simple key-value interface works reliably at scale. The LRU eviction policy works predictably under memory pressure. Its lightweight design enables low-latency access and high throughput across Unix-like systems and Windows.
What does not
It does not handle cache invalidation automatically. It does not persist data. It does not encrypt traffic or authenticate clients. It does not guarantee consistency across nodes.
What it changes
It changes how web applications manage latency: shifting read pressure from databases to RAM, enabling scale without proportional database growth. It establishes caching as an explicit architectural layer—not an afterthought.
Is it worth your time
Yes—if you operate a dynamic, database-driven website and need to reduce repeated reads from slower backing stores. It demands operational discipline around cache invalidation, key naming, and cluster coordination.