In using an Internet Relay Chat (IRC) network, a netsplit is the loss of contact between two IRC servers. As a result, chat users at either end will see the users at the affected servers suddenly disappear.
An IRC network usually has a linear topology. That is, each server is connected in line to the next server which is connected to the next one, and so forth. When two servers lose contact, the network essentially is split into two networks. Users remain in contact with other users on their side of the network split and lose contact with the other users, who appear to have quickly departed. If a network has a mesh topology, each server can route messages to a second server when it loses a server connection.
Most netsplits are restored within a short period of time.