There are generally two types of sites. One type offers the same information to everyone, and the other type offers information that is somehow specific to the person using the site. It’s becoming more and more common to see sites that fall into the latter category, and because of that, it’s becoming more necessary for web developers to be able to design a method of allowing users to log in to a site so they can be uniquely identified.
There are many ways to implement a login system, but almost all of them require a significant amount of code. Not only that, but writing secure code for a login system is difficult because it requires a full understanding of security issues.