What is Memcached?

Memcached is an open source, distributed memory object caching system. It is intended to speed up dynamic web applications by alleviating database load. It caches commonly accessed parts of database driven sites. PHP uses a module to communicate with the Memcached daemon running on the server. Nearly every popular CMS has a plugin or module to take advantage of memcached, and many programming languages have a memcached library, including PHP, Perl, Ruby, and Python. Memcached runs in memory and is thus quite speedy, since it does not need to write data to disk.

PHP Extensions for Memcached

PHP uses two different extensions (memcache and memcached) depending on the CMS you are using for your site and the PHP version it requires for certain themes and plugins being used. The good news is that you can install both versions of the PHP extension on your server to allow your CMS to use them both if needed. The PHP extensions can be confusing as the names are memcache and memcached, however their functionality is similar in that it allows your CMS to perform at optimum levels by caching frequently accessed database components.