One of the features of Facebook is the Chat option for instant messaging with your Facebook friends when they are online at the same time as you are. When you log on to Facebook, your current online status is automatically available to all your online contacts. You can also see who is online and available to chat. Click on any contact's name in the Chat box to start a conversation. Your message will instantly appear in a box at the bottom of your friend's Facebook browser. Sometimes, however, you may not want to chat with a specific friend or group of friends. You have the option of going offline selectively. Sometimes, too many friends are online at the same time, and you don't feel like having to answer anyone. When you are offline you can browse Facebook without anyone knowing you are online at all.
If you want, you can sort your Facebook friends into groups, and give each list a title. Click the white circle next to the title of the list to become invisible to them. You will then appear to be offline to that list only. Even when you are offline to a list, you can still see them in your chat window.
Another option is to go offline to everyone by signing off Chat completely. To disable the "Chat" option, click on the Chat bar at the bottom right of any Facebook page you are currently viewing. When you expand the Chat window you can see all your Facebook contacts that are online. Click on the options menu and select the "go offline" setting. When you sign off Chat, you will not be able to see who is online.