Minecraft wiki entry for Playing_on_servers, associated text: Multiple archetypes of Minecraft servers exist, distinguished by the unique gameplay features, rules, and societal structures which they implement. No two servers are the same, and frequently the line between archetypes is blurred or indistinguishable. Many special types of servers rely on modded versions of the server software, such as Bukkit. Modded server software is not supported by Mojang. Bukkit (and other modified server software) servers may have plugins that modify the experience from the vanilla server. If on a bukkit server, one can type /plugins. You can then do research on what the plugins do.