For the multi-player mod, there is no game servers operated by Mojang. Instead, each having to run a game server. For the Classic mod, there is a public server list, in survival mod to the hostname or IP address of the server you want to be known. Since the final version 1.3 single player worlds run as a separate server, so it is possible to play with other players in a local area network together.
To improve the support of the multi-player mode, the developers of the unofficial multiplayer modification Bukkit on 28 February 2012 set at Mojang, not very common server software is SpoutCraft. How Bukkit server can also expand SpoutCraft with any plugins.
On 15 In July 2012 it has been possible through the use of an exploit in the Minecraft mod login servers to log in with a different user account in the game. After this exploit was discovered, the Minecraft authentication servers have been shut down as a precaution until the fault is corrected was. In an official statement announced Mojang that despite this vulnerability no passwords or other personal information could be spotted.