Someday or later, you'll want to administrate your server from somewhere else than at your server's desk. For this, remote administration exists.
If you install an in-game administration mod such as AMX Mod (x) or AdminMod, you'll gain access to your server while playing, but, what if you're going on vacation and need to access your server from an Internet browser? This is why this whole section exists. Here are simple definitions of what the sub-pages are about: