Here I will explain about differences between asp.net 1.0, 1.1 and 2.0 versions.
Asp.net 1.0 & 1.1 version
In these Asp.net versions IIS should be installed by user.
Asp.net 2.0 version
In this version IIS comes along with dotnet installation no need to install separately and in Asp.net 2.0 many new features has came into picture like partial classes, master pages, skins and themes, roles and membership profiles, Generics and many new controls etc. I will explain each feature clearly. Main purpose of Asp.net 2.0 is used to increase productivity, use same controls for all types of devices, faster and better web application.