So what is a game server? Optimising RUST for FPS is a web server that is used by players that are situated in different places so that you can play together. They connect either locally or remotely to the server and are able to meet each other in the game. Many video games are now being played online, from ones playable in a computer or even in gaming consoles.
A game server can be known as a game host or a shard. It is just a host when a game client also becomes a server, in fact it is a shard when there are plenty of players connecting to 1, like in a multiplayer game. Many companies offering this service are called game providers. There are two forms of game server providers that are available: one which operates their servers using Windows and another one uses Linux and FreeBSD as os's. They allow their clients to change the settings of the server with their liking by providing them with web tools.
Many expert or professional players that belong to many well-known gaming clans pitch in some money to use these servers in order to practice and hone their talents in their game, as many of these players take part in contests that give away a big amount of cash to the winners.