We will be using third-party apps or services by choosing the option to “Login with Facebook”, this means you are giving away part of your personal information to this app. Which means the app will be able to store this information such as our age, full name, email address, friends list, likes, etc., on their servers. This information is enough for that apps or services to have a general idea of who we are.
The problem here is that we sign up for different services on the web and then we use it mostly once or twice and forget. We will not use that app or service anymore but we keep our information shared with that app or service.
Once you are in Apps section, simply select all apps or services that you want to remove and then click on Remove button. Doing this will prevent the app or service from accessing your information in the future. But you cannot delete the information which is already shared with the app or service.
Be sure to check Apps section once in a while and remove the apps you no longer use. Doing this may help you future data thefts on Facebook.