What does the ~ next to someones nick mean?
This means that that person is a channel founder in the respective channel he/she is in. What does it mean to be a channel founder? Well, channel founders are just that – they were the first person to register the channel with ChanServ, hence “founded” it. Channel founders have all the same privileges of channel operators, channel protected users, and more. No one can kick or deop a channel founder. Additionally, only channel founders can set channel modes +u and +L. Generally there are never more than two channel founders per registered channel, and often only one. Channel founders are the last stop in channel authority.