Use the Available status when you are at your computer and able to chat with your contacts. You can set a custom message for this status.
Use the Busy status to let your contacts know that you don’t want
to chat right now. They can still contact you, for instance if they have something
urgent they need to discuss. By default,
Use the Away status when you are going away from your computer.
When you set your status to Invisible, you will appear as offline to your contacts. You will still be connected to your accounts, and you still see your contacts’ statuses and start conversations with them.
Setting your status to Offline disconnects you from all of your accounts.