.NET Framework 3.5 SP1 (Full Package)
Note: As Microsoft updates its download centers, always verify the digital signature of the downloaded file. The legitimate offline installer is typically between 230 MB and 280 MB. The standalone dotnetfx35
Introduced Language Integrated Query (LINQ), new compilers (C# 3.0 and VB 9.0), and enhanced support for AJAX and RESTful services. The standalone dotnetfx35
The standalone dotnetfx35.exe works directly as an offline installer for these systems. It will install .NET 2.0 SP2, 3.0 SP2, and 3.5 SP1 in one go. The standalone dotnetfx35
Advanced data access technology that evolved how developers interact with relational databases. Download & Installation Guide
Modern Windows versions already have these files hidden in the system; you just need to "turn them on." Start Menu "Turn Windows features on or off" , and press Enter. Check the box for .NET Framework 3.5 (includes .NET 2.0 and 3.0)