In most cases, the person that first joins a channel automatically gets operator status, and is later referred to as the channel founder, which usually gives them further privileges on networks with ChanServ. Channel operators can also voice (+v) and op (+o) other users in the channel. On networks with no channel services, abuse of netsplits is common to gain operator status in certain channels.
Some servers feature halfops (+h). These users are privileged in a certain channel, though not as powerful as ops. Halfops may kick other users out of the channel and set most channel modes. In addition, they can also set voice (+v) to all users. They are not allowed to make other users ops or halfops. This is supported on IRCds such as UnrealIRCd and UltimateIRCd. Other IRCds, such as Bahamut and IRCu, do not have halfops.
IRC bots are often used to automatically op certain users upon joining the channel. They can help out maintaining the channel by doing tasks typically done by a channel operator such as kicking and/or banning users who spam, flood, curse or otherwise break channel rules.
In some IRC clients (notably mIRC), ops and halfops are represented by an "@" or a "%", respectively, prepended to the user's name in the channel's userlist.