The privacy and visibility settings on Facebook accounts allow users to control the amount of information they share with friends, contacts and other users of the social networking site. One option is to block another user completely. This removes the blocked individual from the user's Facebook friends list, hides all content on the account, and removes the user and all his content from the blocked individual's Facebook searches. If a user blocks you on Facebook, that user becomes invisible to you.
Facebook allows friends and contacts to communicate and share photos, videos and other content online. However, some people abuse Facebook, using their accounts to harass other users or to send spam posts across the social network. The Facebook "Block" feature allows users to block another person for any reason. This might be because of spam posts, inappropriate content, and harassment or for a more mundane reason -- for example, because the user does not want a boss, co-worker or former partner to see his Facebook account.
Blocking someone on Facebook is straightforward. A user can block you by clicking a link on the bottom of your Facebook profile, clicking a link from a drop-down menu beside any of your posts or comments, or by entering your name into the Block List tool on his Facebook account's Privacy Settings page. Facebook makes it easy to block users so that each user personally controls who can view and access his Facebook profile and content.
Facebook will not notify you if another user has blocked you. You are ] likely to know if another user has blocked you only if that person suddenly disappears from your Facebook friends list or goes missing from your own friends list when he vanishes from Facebook search results, Facebook groups, Facebook pages and other site content. If another user has also reported you for activities that breach Facebook's terms and conditions -- spam or harassment, for example -- Facebook may suspend your account or permanently deactivate the account.
Once another user on Facebook has blocked you, you have no way of appealing to the site's administrators. Facebook allows each user discretion over whom to block and will not reverse a user's decision. The only person who can "unblock" you is the user who blocked you in the first place. If you believe that someone has accidentally or mistakenly blocked you, the only way to reverse the decision is to contact the person off of Facebook and ask him to unblock you. Unblocking will not automatically restore you to his friends list. For that, he will need to accept your friend request after he has unblocked you.