Game server

A game server is remotely or locally run server used by game clients to play multiplayer games. Most video games played over the internet operate via a connection to a game server.

Types of game servers
Game servers can be classified as listen servers and dedicated servers. Listen server refers to a situation in which the server typically runs in the same process as the game client, allowing a player to both host and participate in the game. As a side effect, the server is usually terminated when the client is. Listen servers are operated mostly by individuals, often in LAN situations rather than over the internet, and usually with a lower number of players due to the increased processing and bandwidth requirements associated with operating both server and client simultaneously on the same machine.
Dedicated servers are servers which run independently of the client. Such servers may be run by individuals, but are usually run on dedicated hardware located in data centers, providing more bandwidth and dedicated processing power. Dedicated servers are the preferred method of hosting game servers for most PC-based multiplayer games.
Massively multiplayer online games run on dedicated servers usually hosted by the software company that owns the game title, allowing them to control and update content. In many cases they are run on clustered servers to allow for huge environments and large player counts.

Game server hosting
Game server providers (GSPs) are companies that lease dedicated game servers. Gaming clans will often lease one or more servers for their chosen game, with members of the clan contributing to the server rental fees.
Game server providers often offer web based tools to help control and configure the individual game servers and most allow those that rent/lease to modify the games being leased.