Foundations of Programming and The Code Wiki Book by Karl Seguin

Karl Seguin allowed me to copy and display on my site PDF copies of his articles. I found it more convenient than to download original ZIP versions (zipped PDF of Foundations of Programming was created by Tim Barcz).
According to Karl, you are allowed to copy, distribute and display articles, provided that you always attribute articles to him, do not use them for commercial purposes and do not alter in any way.
Unzipped PDF documents allow for reading online. These articles are very interesting. Look at Karl's The Code Wiki site and read his blog.

For better understanding of what N-Tier and Domain-Driven Design are, I would probably recommend to read 2 chapters of The Code Wiki Book first, then to read Foundations of Programming article and finally, to read Building Layered Web Applications with Microsoft ASP.NET 2.0 article by Imar Spaanjaars as a good and simple practical example of N-Tier DDD approach.