caching

What are the advantages of using server caching? and how can I implement it to improve website loading time?

I have a xenforo forum and looking for a caching to speed up my forum, which is the best Xenforo 2 caching plugin?

Currently, the Memcached module supports 2 versions and each of these versions will support different types of PHP: php-memcached 3.x: - Supports PHP 7.0 - 7.1. - Requires libmemcached 1.x or higher. - Optionally supports igbinary 2.0 or higher. - Optionally supports msgpack 2.0 or higher...

What command on SSH to check and know on how much RAM my Memcached used? I assigned 1GB of RAM to cache size for my memcached but not sure how much it used? Does anyone know how to check memcached stats?