You're only online on IRC while you're connected to it. When you disconnect your client, your username disappears from the list and you cannot receive private m

You're only online on IRC while you're connected to it. When you disconnect your client, your username disappears from the list and you cannot receive private messages or see conversations in IRC channels. One user == one open TCP connection. A bouncer holds that TCP connection for you and you connect to it instead of directly to the server. It will store messages received while you were away, automatically log conversations to disk, and allow you to connect to the same user with multiple devices, among other features.