c# - Namespace or Assembly?

Question

I am getting very confused between Namespaces and Assemblies. Are System.Data and System.Web Namespaces or Assemblies?

I have noticed these are called namespaces and at the same time they are present in GAC_32 folder. So what exactly are they?

Answer 1

System.Data is a namespace, System.Data.DLL (the file) is an assembly.

A namespace is a logical grouping of types (mostly to avoid name collisions). An assembly can contain types in multiple namespaces (System.DLL contains a few...), and a single namespace can be spread across assemblies (e.g. System.Threading).