Operator

for more goto: http://www.mrcreeperhuggers.co.uk/minecraft-multiplayer-commands.php

An Operator, or op, is a player designated to moderate a multiplayer server by the admins and the owner of the server. This is done to help keep control of the server from unruly players and Griefers, and even a reward to trusted players. People are made operator by using the /op command, or by editing "ops.txt" text file in the server, then restarting the server. Operators have access to a variety of server commands which aid them in their policing duty. These are activated by typing them into the chat with appropriate arguments.

Operators also are granted the privilege of destroying and placing blocks. Although the admin can also decide to let all players destroy and place blocks.

Problems with untrustworthy operators
Operators have access to all commands meaning they can stop the server, control any plug-ins (such as spawning large amounts of mobs or removing entire chunks [when using server software that supports plug-ins]) and kick/ban admins,the server owner, griefers and non-opped players.

This can be avoided in Modded servers with any permissions plug-in. This disallows some operators the right to use certain commands.

If a [op] takes the power for granted then you can take them off the [op] list mt using the command. [deop]

Operator commands
See Server commands.

Opérateur