Bots are not looked on favorably by most Networks. They are even banned by many servers. Bots have been given a bad rap due to misuse and abuse by hackers. Bots can, however, be very useful if properly programmed. They can be user to hold a channel open when the owner is not physically there on the channel, they can be set up as a file server to offer files to people, they can be uses as help and information servers, or they can even be used to run games on a channel.
Bots can range from the very simple to the very complex.
The most powerful Bots are run on ircll client programs, which is a UNIX based system. Bots are not for everyone, and I would advise you not even consider using one. A Netsplit is the loss of communication between servers on a Network. When a netsplit occurs, users will appear to leave the channel in large numbers almost simultaneously. You may even find yourself left as the only person on the channel.