What's new in the .NET framework version 3.5

1. Framework - 3.5 extends many new features like Linq, WCF those are useful to develop pocket PC, smart phone and distributed mobile applications.
   

2. ASP.Net -
1. 3.5 includes AJAX while in 2.0 it needs to install. Microsoft AJAX library supports client-centric, object orient development which is browser independent. ScriptManager to make a page AJAX enable. UpdatePanel to target a specific area of page rather than refreshing whole page.   
2. Visual web developer includes improved intellisense for java script and Ajax library.
3. Listview control displays data provided by data source by using user defined templates. User can select, insert, update, delete and sort records. Listview includes features of data grid, grid view, data repeater and other similar list controls available in 2.0.
4. Data pager provides paging functionality to data bound controls those implements ‘Ipageableitemcontainer’ interface like listview control.
5. LinqDataSource for Linq(Language integrated query).
6. ASP.Net Merge Tool to merge precompiled assemblies (aspnet_merge.exe) .

3. Add-Ins and Extensibility - 3.5 introduces new architecture and model that enables powerful and flexible support to developers to develop extensible applications.
   
   
4. CLR – 3.5 has improved CLR. Also has improvements in collection, garbage collection, better reader and writer locks in threading, i/o and pipes, reflection, diagnostics etc.
   
   
5. Cryptography – 3.5 includes improved features for security. Some new cryptography classes added those used to verify and obtain information of manifest signature. 3.5 supports suite B cryptography algorithms published by National Security Agency(NSA).
   
   
6. Networking – Several features of networking get improved in 3.5. Peer to peer networking is server less networking technology allows network devices to share resources and communicate with each other directly, is get improved in 3.5.
   
   
7. LINQ – Its a new feature in 3.5 extends powerful query capabilities to language syntax of C#, VB.Net. Its standard, easy to understand and learn. 3.5 extends some assemblies those enable the use of Linq to query .net collections, databases, xml documents, ado.net data sets.
   System.Linq – (exist in System.core.dll) Extends standard operators and types for Linq.
   System.Data.Linq – Enables interaction with databases.
   System.Data.Linq.Mapping – Enables to generate Linq to Sql object model.
   System.xml.Linq – Enables Linq to access and modify xml documents.
   
   
8. Expression trees – Expression trees are new in .net 3.5, it provides a way to present language level code in the form of data.