Knowing what you intend to use it for would influence the suggestions.

Also, .NET was supposed to be this grand Java killing development platform from Microsoft. Of course, interest in the company has fizzled on it quite a bit, and developer pickup was slow.

Basically, it's a set of tools for developers to write programs with. It was supposed to make things easier for developers to create programs, and help prevent some of the problems that have plagued Windows pretty much since the beginning. Any description beyond that would only be of interest to developers.