The .NET framework is a basis for other programming languages including C#, VB.NET and F#. It is often used for data-driven applications and is extremely popular in the UK, with alternatives usually being Java or Python.
At Eastpoint, we have lots of experience with the Microsoft stack - and we mean lots. Our work with .NET covers ecommerce, web applications, and mobile apps.
Recently, .NET became open source, which may be a consideration for your project.
We're also Microsoft Partners, with silver status for application development.