Quote

The caching method is used by various systems for temporary data storage and data caching. All options apart from Memcached use server memory and using any of these will increase performance over not caching. Memcached is a distributed memory object caching system and provides the best performance.

All options apart from Memcached use server memory? If I understand english right it's wrong. Memcache (memory cache) - use only memory cache. Not apart

Memcached may or may not use server RAM. This method allows you to configure another server (different IP address) to hold the caching mechanism and then use this other server's RAM. But I agree with you, the wording there could be better.