This document introduces .NET as a free, cross-platform, and open-source software development platform that can be used to build all types of applications. It highlights that .NET supports popular programming languages like C#, F#, and Visual Basic and can be used across desktop, web, cloud, mobile, gaming, IoT, and AI development. The document also provides testimonials from various companies on how .NET has helped them build applications and notes its growing adoption and active developer community.