When you log in to your personal Facebook account, people can initiate chats with you or send you messages. There are basically two things that enable other people to detect when you’re online: your activity and the Chat feature. Even if you don’t post anything and don’t comment on anything, the Chat feature displays you as online to your friends. So to get on Facebook without people knowing you’re online, you need to make sure the Chat feature is turned off. Tips Writer Bio
