How to implement user authentication in your web application

When you are building web sites then you will often need to implement a user authentication mechanism. Be it a Java, PHP, Grails, or whatever technology based site – the issues are the same.

Researching for authentication I found this article: http://www.openwall.com/articles/PHP-Users-Passwords

It is written for a PHP programmer audience, but it touches all the  subjects and makes a really interesting read – highly recommended!