I imagine just about everyone in programming has heard of the Gang of Four (GoF) design patterns.  The GoF were the four authors of the well-known book Design Patterns: Elements of Reusable Object-Oriented Software.  This book was the foundation for many of the popular design patterns that are currently in use and served as a significant source for object-oriented theory.  It was originally published in 1995, but there is still so much demand for the book that it continues to be printed and sold over ten years later (which is rather impressive for a technical book IMO).

Design patterns are a very important part of software development.  They provide a proven, recurring solution for many common problems that arise from project to project.  It can easily make the difference between a sound solution and a maintenance nightmare. Any good developer or architect should possess a sound understanding of the fundamental design patterns.  Unfortunately, I know a lot of people in the industry that consider design patterns to be purely for academia with little practical use in the real world.  (I am not one of them!)

At any rate, I finally come to the original purpose of this post.

There is a great site to get a better understanding of the GOF design patterns: www.dofactory.com.  They have a description for each pattern along with UML diagrams and example code.  You will find the majority of the information to be available for free.

I have known about this site for quite some time and referenced it on numerous occasions for brushing up on patterns that I don't use very often.  However, I was recently on their site and decided to purchase their premium product.  I was very pleased with the content, so I thought I would mention it on my blog.  The download contains a complete VS2005 solution containing all of the code for each pattern listed on their site, code for additional patterns not listed on the site, Visio UML diagrams, and code for a website that demonstrates real-world use of several different patterns.  The code is available in C# or VB.NET.  You can view the details of the offer here: http://www.dofactory.com/Framework/Framework.aspx

If you are interested in learning more about design patterns, it is definitely a resource worth consideration.