Facebook is a popular online social networking website. When someone logs into Facebook, that person's Facebook friends can see that he is online through the instant messenger built into Facebook. The Chat feature allows people to send instant messages with their friends that are signed into Facebook. If you do not want other people to know that you are online, you can change your status on Facebook Chat.
Log in to your Facebook account.
Click on the "Chat" tab located in the bottom right corner of your Facebook screen.
Click "Options," and then click "Go Offline." When you are offline, your Facebook friends will not know that you are using Facebook and they cannot send you messages through the Chat feature. Your account will save your offline status until you change it. Every time you log into Facebook, you will appear offline, and your Facebook friends will not know that you are online.