Answer
dot NET is a free, open source developer platform created by Microsoft for building many different types of applications, including web, mobile, desktop, gaming, IoT, and cloud based applications. It consists of a runtime that executes your code, a set of programming languages like C# and F#, and a huge collection of libraries that provide ready made functionality, all designed to work together so developers can build applications efficiently using consistent tools regardless of what type of application they are creating.
// One platform, many app types
dotnet new console
dotnet new webapi
dotnet new mvcReal-world example A startup builds its customer facing website, its internal admin tool, and its backend API all using dot NET, letting the same team of developers work productively across every part of the product using shared knowledge and libraries.