complete and secured registration and login system in php and mysql important concepts and features in this project connect to mysql and create database object using objects with PDO (php data object) validation and security front-end form validation back-end php script secured password hashing (with php hasing algorithm) register and authenticate user send account activation link via e-mail display and update user profile information automatically logoff inactive users (when they are inactive over a predefined period of time) reusable code(custom functon) cross site request forgery and lots more (to protect your site) requirements development environment, runing php 5.5 or higher (i am using php 7.0.9)