A ROBLOX game server is an instance of ROBLOX's game software running on ROBLOX's servers. Servers will generally host more than one game server, which will each be instances of game servers serving different places. When a user joins a game, his client, an instance of the ROBLOX software on his computer, requests for a game server to be created if all of them are full or if there is no server, and then connects to it. Other clients on the computers of other users may then connect to that game server. This is the base of ROBLOX's multiplayer system.
Whenever a changes occurs on a client (character movement , chatting , etc.), it is replicated to the server, which then replicates it to all the other clients connected to the game. Similarly, whenever a change happens on the server (generally because of the physics, or because of scripts), it is replicated to all the clients connected to the game.
- Sometimes, players would join a server to meet a famous or popular player.