Memcached is a high-performance, distributed memory object caching
system, generic in nature, but intended for use in speeding up dynamic
web applications by alleviating database load.

Danga Interactive developed memcached to enhance the speed of
LiveJournal.com, a site which was already doing 20 million+ dynamic
page views per day for 1 million users with a bunch of webservers and a
bunch of database servers. memcached dropped the database load to
almost nothing, yielding faster page load times for users, better
resource utilization, and faster access to the databases on a memcache
miss.