Facebook does not offer a feature which allows users to know who looked at their profile. Although some third-party apps claim to offer this feature, it is not possible. Facebook encourages users to report apps that claim to offer this feature.
Users who are concerned with sharing personal information on Facebook can adjust their privacy settings. Information such as current city, education, current employer, family and interests can be blocked from view by changing the settings. Changes to privacy settings immediately take effect.
Facebook allows users to even block pictures and videos. Audiences can be limited to friends, friends of friends, and select individuals.