What is Facebook Log In? Facebook Login In means asking user to grant access to his/her facebook information like email id, username, friends, posts etc.If your website is allowing login using facebook then your website is considered as an facebook app. Facebook SDK for PHP helps developers connect with graph api and leverage Facebook login in their websites.hello sir this tutorial is very helpfull but sir i want to login with facebook using codeigniter so if you have any solution please help. How to login to websites. Questions and Answers.Login to Facebook.