C# language version history

The evolution of C# has transformed it into a modern, high-performance language. This guide tracks every major milestone.

The Early Years (C# 1.0 – 1.2)

C# launched in 2002 as a primary language for the .NET Framework. It felt like Java but with a focus on Windows development. Version 1.2 arrived shortly after with small improvements like IDisposable support in foreach loops.

The language had the following goals:

• It is intended to be simple, modern, general purpose, and object oriented programming language.
• It should include strong type checking, array bound checking, detection of attempts to use uninitialized variables, source code portability and automatic garbage collection.
• It is intended for use in developing software components than can take advantage of distributed environments.
• As programmer portability is very much important, especially for those programmers already familiar with C & C++, C# is best suitable.
• Provide support for internationalization, as it was very important.
• It is intended to be suitable for writing applications for both hosted and embedded systems.

Source: C# design goals

Major Productivity Shifts (C# 2.0 – 5.0)

These versions introduced the features we use most today.

• C# 2.0: Generics, anonymous methods, and nullable types changed how we handle data.
• C# 3.0: LINQ, lambda expressions, and extension methods made querying data much easier.
• C# 4.0: This version added the dynamic keyword and optional parameters.
• C# 5.0: The async and await keywords revolutionized asynchronous programming.

The Modern Compiler Era (C# 6.0 – 9.0)

With the Roslyn compiler, updates became faster and more frequent.

• C# 6.0 & 7.0: These versions focused on “syntactic sugar” like expression-bodied members and tuples.
• C# 8.0: Nullable reference types helped developers avoid common null-pointer exceptions.
• C# 9.0: Records and top-level statements simplified data modeling and reduced boilerplate code.

Recent Advancements (C# 10.0 – 13.0)

The language now evolves annually alongside .NET.

• C# 10 & 11: Global using directives and raw string literals improved developer productivity.
• C# 12 & 13: Primary constructors for classes and ref struct improvements kept the language competitive.

What’s New in C# 14?

Released with .NET 10, C# 14 introduces several quality-of-life improvements.

The field Keyword

You no longer need to manually declare backing fields for properties. The field keyword allows you to access the compiler-generated field directly inside accessors.

public string Name { 
    get => field; 
    set => field = value ?? "Unknown"; 
}

Extension Members

C# 14 expands extension methods. You can now define extension properties, static members, and even operators within a new extension block.

Other Key Features

• Null-Conditional Assignment: Use ?.= to assign values only if the target is not null.
• Implicit Span Conversions: Arrays and strings now convert to spans more naturally.
• Lambda Modifiers: You can use ref, in, and out on lambda parameters without explicit types.
• Partial Constructors: Source generators can now define signatures for constructors in partial classes.