.NET is a development platform created by Microsoft for building software of almost any kind: web apps, APIs, desktop programs, mobile apps and cloud services. It bundles a runtime that executes the code, a large library of ready-made building blocks, and tools that tie it all together. Most .NET software is written in C#.
A helpful way to picture the difference between a language and a platform is a kitchen. C# is the recipe you write, the instructions for what to cook. .NET is the fully fitted kitchen: the oven, the pans, the running water and the well-stocked pantry that make the recipe possible. You could write the recipe on paper, but without the kitchen nothing gets cooked. As a framework and runtime combined, .NET supplies that environment so developers do not rebuild common machinery for every project.
In practice you reach for ASP.NET Core to build web APIs and sites, Entity Framework to talk to a database, and Blazor if you want to write interactive web pages in C# instead of JavaScript. Microsoft ships a new major version roughly every November, with even-numbered releases getting longer support, so teams plan upgrades around that rhythm.
Modern .NET, the line that started with .NET Core, is open source and runs on Windows, macOS and Linux. An older Windows-only version called .NET Framework still powers many established business systems, which is why you will hear both names. The catch is that the two are not the same thing under the hood, so moving an old Framework app to modern .NET takes real porting work, not a flick of a switch.
At TopDevs we build a lot of client back-ends on .NET because it pairs Microsoft’s long-term support with the speed and cross-platform reach modern projects need.
