Memcached

Memcached is a high-performance, distributed memory object caching system designed to speed up dynamic web applications by reducing database load. Originally developed by Brad Fitzpatrick for LiveJournal, it has become one of the most widely deployed caching systems on the internet, used by companies like Facebook, Wikipedia, Twitter, and YouTube.

The concept is simple: Memcached stores key-value pairs in memory across one or more servers. Applications check Memcached before querying the database. If the data is in cache (a cache hit), it is returned in microseconds. If not (a cache miss), the application queries the database and stores the result in Memcached for future requests. This pattern can eliminate 80-95% of database queries on a typical dynamic website.

Memcached is intentionally simple. It provides a key-value store with get, set, delete, and increment/decrement operations. Keys can be up to 250 bytes and values up to 1MB by default. There are no complex data structures, no persistence, no replication, and no authentication in the base protocol. This simplicity is by design, keeping the system fast and predictable.

For hosting environments, Memcached is commonly deployed as a session store and object cache for PHP applications. WordPress, Drupal, Magento, and most PHP frameworks support Memcached natively or through plugins. On shared hosting servers, each account typically gets a dedicated Memcached instance with a memory limit (usually 64-256MB) to prevent resource abuse.

Compared to Redis, Memcached is simpler and uses less memory per key for basic caching workloads. It supports multi-threaded operation, allowing it to use multiple CPU cores more efficiently than single-threaded Redis for pure caching scenarios. However, Redis offers more data structures, persistence, and features. Many hosting providers offer both options.

Memcached is straightforward to deploy and requires minimal configuration. The default settings work well for most use cases, making it an easy performance win for hosting providers looking to improve site speed across their platform.