Memcached
In plain terms
A simple, high-performance in-memory caching system.
Going deeper
Memcached caches key-value data in RAM to speed up applications by reducing database hits. It's deliberately minimal and fast.
Under the hood
Multithreaded and pure cache (no persistence or rich types), simpler than Redis for plain caching.
Examples
Database query caching, session caching, reducing DB load, web acceleration.
Think of it like...
Like a fast scratchpad for temporarily holding hot answers.