Authentication system

Authentication is fairly common in web technology this days, where web-based application are becoming widely use by different categories of users, for example you may have a web application that grant certain privilege to a particular user, such as Top level management or Administrative staff and deny low-level staff such as supervisor or marketer some of this administrative privileges.
If my example is too corporate, let’s take facebook for an example, it is authentication that allow facebook to secure your account, using the registration and login you did, to track and manage your activities, for example when you login you can access you message, chat history, wall update, friends list and more, all this and more is made possible using an authentication system.
Because most of the web application or software you will be building will involve some authentication such as, User Registration, User Login, Change Password Page and Welcome page, that is why I decided to put this chapter together to explain how this is done. I hope you enjoy it.