Server

Minecraft servers allow players to play online with other people. They may either be run on a dedicated server, or be temporary, and run off a home machine.

How to Setup a Server
Download the official server software from the Minecraft multiplayer page or custom server software.

For installing and running the server check here.

For instructions on running a server on Mac OSX check here.

Connecting to Your Local Server
Select the "Multiplayer" option in the game client (or browser client), and type in the local address (e.g. 127.0.0.1) include the port number only if you aren't using the default (25565TCP and UDP) (e.g. 127.0.0.1:1234).

Server Information and Known Issues
See the known bugs page for known single/multiplayer issues.

The server commands page has a list of useful commands.

Types of Servers
There are numerous kinds of Minecraft servers, usually distinguished by the level used in them or how players in them are supposed to behave. Many special types of servers rely on the use of map editors.

Standard
Standard servers usually have relatively regular maps, allowing players to build or destroy whatever they want (though griefing is often against servers' rules).

Survival Multiplayer
Also referred to as SMP. A type of Standard server, in which survival against monsters is key. Time of day is generally not tampered with unnecessarily, to provide players with a sense that they are in a singleplayer-type environment, with other players in the world.

Falling Lava
A form of roleplay, falling lava servers usually use a small map with a single block of lava or a lava "timer" (a long channel through which lava flows, delaying its spread) at the top of it. Players are intended to try to construct a shelter so as to "survive" before the lava engulfs the map; the map usually reset/restored sometime afterwards. Some maps use water in the place of lava to make building after the flood easier.

Roleplay
A server, usually with a normal map, where players are encouraged to take on roles and act as them in the game. These servers often attempt to simulate settlement in some foreign land or similar, and require the gathering of resources to build structures.

Spleef
Spleef servers are usually dedicated to playing Spleef. They use a nonstandard map which contains Spleef arenas, of which are generally much more extravagant than those a standard server might have.

Grief
Though rare, a grief server usually consists of another server's map which the grief server's owner would retrieve, therefore allowing people to "grief" without getting banned.

Randomly Generated
A map design generated using either the standard in-game generator or an external generator such as Omen. While the in-game generator can only create temperate-themed maps, desert-, mountain-, hell-, snow-themed maps and others can be created with external generators.

Flat
An otherwise standard design which is not randomly generated, but is instead simply a vast grassy plain. These are usually created by various external generators.

Ocean
Ocean maps usually consist of mostly or entirely water to encourage building underwater structures; they may also be dry at first, but flooded later, after players have built on them. These gained more prominence when sponges were added.

Cave
A server which is mostly or entirely an elaborate cave or series of caves, far more spacious and dynamic than standard caves. These commonly have the top and sides blocked off with bedrock to stop light getting through.

Landscape
Landscape server with widely varying features across the map, such as caves, forests, mountains and oceans. These are commonly custom-made and used in roleplay.

Delete Player
If you want to delete a player from the game, you can remove the player's .dat file. Navigate to the Minecraft home directory, open the map folder, open the player's folder, and delete the PLAYERNAME.dat file. This will cause the player to start over at the spawn point with no inventory. The player's changes to the world will be unchanged along with any inventory stored in chests.

Converting A World after 1.3
After the 1.3 beta update, a new method of saving maps implemented. This lead to all old saves needing to be converted. However this also broke multiplayer world. You can convert them by copying the folder that your world is name (by default "world") found in the same folder you use to edit ops and banned IPs. Copy this folder in to your .minecraft folder called "saves" (easily reached by clicking "texturepacks folder" button on the texturepack menu screen of the game client) and then converting it like you would convert a normal single player save, and then moving it back to your multilayer server folder.

Server