I'm not sure what language you're used to, but the .NET package system isn't that hard to work with. Assemblies: think JAR files, Python eggs, Ruby gems. They

I'm not sure what language you're used to, but the .NET package system isn't that hard to work with. Assemblies: think JAR files, Python eggs, Ruby gems. They're collection of classes, which can be grouped into modules. Modules: a collection of classes. 99% of the time, there is one module in an assembly. Modules are effectively invisible for developers in all contexts; they really come up when you combine a pile of existing assemblies into one big master assembly for distribution, in which case that master assembly will have multiple modules, but as a developer, the main way that this would show up is that the things that were previously their own assemblies still act as if they're all in separate assemblies. The GAC: This is what it sounds like: the global assembly cache. It allows multiple programs to safely use the same DLL, so that you only need to have one copy on your machine. I've not actually heard of people getting totally lost in the .NET 2 to 4 transition, but I'm sure it's happened. That said, that's also happened in the Go world (especially due to their lack of versioning), in the Python world (especially as 2 to 3 starts actually happening), in the Java world (where someone didn't specify full versions for what JARs they were using, and the new ones conflict), and a bunch of other environments. I don't consider that .NET-specific.