Server Commands/JOIN
Syntax: JOIN <#channel1[,#channel2,#channel3...]> [key]
The JOIN command allows you to enter a public chat area known as a channel. Network wide channels are proceeded by a '#'. You can join more than one channel at a time, separating their names with comma's (',').
If the channel has a key set, the second argument must be given to enter. This allows channels to be password protected.