Microsoft released ASP.NET 3.5 on November 19, 2007. Along with it, was released Visual Studio 2008. This evolution from ASP.NET 2.0 to ASP.NET 3.5 is quiet gradual. ASP.NET 3.5 uses the same engine as that of ASP.NET 2.0, with some extra features added on top of it.

Added Features:
Language Integrated Queries (LINQ) Family of technologies that provides querying features for data,
From relational to XML Generate a LINQ object model that provides an object representation of the database
New collections: HashSet Peer-to-Peer networking framework Integration of WCF and WWF (Workflow Services)
New ASP.NET Data Controls and Extensions are added.

Some Important Points
1. ASP.NET 3.5 provides better support to IIS7. IIS7 and ASP.NET 3.5 modules and handlers support unified configuration.
2. You can have multiple versions of ASP.NET on the same machine.
3. For those who are wondering what happened to ASP.NET 3.0, well there isn’t anything called ASP.NET 3.0.
4. VS 2002 worked with ASP.NET 1.0, VS 2003 worked with ASP.NET 1.1, and VS 2005 worked with ASP.NET 2.0. However VS 2008 supports
multi-targeting, i.e it works with ASP.NET 2.0, and ASP.NET 3.5.

By: Suprotim Agarwal