your previous question is almost the same, see that thread: http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/111/threadid/270731/scope/posts/Default.aspx

also: the homepage of DotNetNuke.com explains in high level what dnn is, did you have any specific questions about that?

DNN Blog | Twitter: @erikvb | LinkedIn:

You did made mistake but I am not going to re-write what other just said. But please be more careful in future and also be some more specific about question you ask.

You can see what "DotNetNuke Is" on DNN's home page (just search for text on http://www.dotnetnuke.com. That gives you sky view of what is DNN.

We can also write DNN in most simple way - DNN is web application framework that let you create web site / portals in very easy way. Also it is very very easy to manage content for site. And if you know how to create UserControls in asp.net - you know how to create Modules for DNN.

If you don't know what module is - say its plugging for DNN. And as plugging behaves - you can add/remove/upgrade modules directly on server without touching rest of the code/site.

I would suggest you to read some book on DNN to gain knowledge.