C# is a multiparadigm, managed, garbage-collected, object-oriented programming language created by Microsoft in conjunction with the .NET platform.

C# is also available in non-Microsoft implementations (most notably, Mono).

Versions 1.0/1.2 and 2.0 of C# were submitted and approved as both ECMA and ISO/IEC standards. As of December 2010, there are no ECMA or ISO/IEC specifications for C# 3.0 and 4.0, however language specifications are available from Microsoft (3.0 and 4.0 respectively).

The language's type-system was originally static, with only explicit variable declarations allowed. However, the introduction of var (C# 3.0) and dynamic (C# 4.0) allow it to use type-inference for implicit variable typing, and to consume dynamic type-systems, respectively. Delegates (especially with lexical-closure support for anonymous-methods (C# 2.0) and lambda-expressions (C# 3.0)) allow the language to be used for functional programming.

Compilation is usually to the Common Intermediate Language (CIL), which is then JIT-compiled to native code (and cached) during execution in the Common Language Runtime (CLR); however, options like Ngen (.NET) and AOT (Mono) mean this isn't the only option. Additionally, some frameworks (e.g. the Micro Framework) act as CIL interpreters, with no JIT.

Perhaps unusually, generics in C# are provided (in part) by the runtime, unlike (for comparison) C++ templates, or Java's generics (which use type-erasure).

With the combination of Microsoft .NET for Windows (desktop/server), Mono (desktop/server/mobile), Silverlight / Moonlight (browser/mobile), Compact Framework (mobile), and Micro Framework (embedded devices), it is available for a wide range of platforms.

In November 2014, Microsoft announced the decision to Open Source .NET with Apache 2.0 Open Source licensing and to begin supporting iOS, Linux, and Android in addition to Windows as platforms for .NET 2015 (5.0) and ASP.NET 5.0. As a result C# can now target all these platforms using a single code base through Visual Studio 2015 (currently available for preview).

Hello World

using System;
class Hello
    static void Main() 
        Console.WriteLine("Hello, World");

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Code Language (used for syntax highlighting): lang-cs