[tapoxi]

An IRC channel is hosted by a network of federated servers (such as Freenode or EFNet). This is why netsplits happen when communication is disrupted between servers.

Some networks have bolted-on authentication to prevent people from riding netsplits and commandeering channels, but that's not a part of IRC itself.

[claudiawerner]

I'm interested in knowing more about this. Accessing #xyz on Freenode won't let me access the #xyz on EFNet, I don't understand how the servers are linked or to what effect. Surely I have to be connected to Freenode to talk in a Freenode channel? Similarly if Freenode goes down, is the channel I was using still accessible somehow else?

[tjoff]

Freenode and efnet are completely separate. But both freenode and efnet have lots of servers (typically spread out geographically) that are synchronized and it's between those that a split can occur.

People in channel #xyz on efnet doesn't have to be connected to the same server to talk to each other (during normal operation).