The History of C#

The story of C# begins in the late 1990s at Microsoft. A team led by lead architect Anders Hejlsberg set out to design a new language for building modern software on Windows. The result was first released to the public in 2002, alongside Microsoft's new ".NET Framework".

Who led the design of C# at Microsoft?

The name "C#" comes from music notation, where a "sharp" (#) raises a note by a half step — hinting that C# is a step up from the older language C. Visually, the "#" symbol also looks a bit like four "+" signs packed together, a playful nod to C++, another language C# borrowed heavily from.

The "#" in C# comes from music notation, where a "____" raises a note by a half step.

C# has kept evolving steadily ever since. C# 3 (2007) introduced LINQ, a powerful way to query data. C# 5 (2012) added async/await for writing responsive, non-blocking code. C# 9 (2020) arrived alongside .NET 5, the release that unified Microsoft's once-separate ".NET Framework" (Windows-only) and ".NET Core" (cross-platform) into a single, modern ".NET" platform.

Unlike many older Microsoft technologies, C# and .NET are open source today. Their source code is publicly available on GitHub, and developers all over the world — not just Microsoft employees — contribute improvements to the language.

C# and .NET are open source, with source code publicly available on GitHub.