C#.Net versions over the years

C# version .Net Framework Visual Studio Released Major new features
C# 1.0 .Net 1.0 VS 2002 January 2002  
C# 1.2 .Net 1.1 VS 2003 April 2003 First version to call Dispose on IEnumerators which implemented IDisposable
C# 2.0 .Net 2.0 VS 2005 November 2005 generics, anonymous methods, nullable types, iterator blocks.
C# 3.0 .Net 3.5 VS 2008 November 2007 lambda expressions, extension methods, expression trees, anonymous types, implicit typing (var), query expressions.
C# 4.0 .Net 4 VS 2010 April 2010 late binding (dynamic), delegate and interface generic variance, more COM support, named arguments, tuple data type and optional parameters.
C# 5.0 .Net 4.5 VS 2012 August 2012 async programming, caller info attributes, Breaking change: loop variable closure.
C# 6.0 .Net 4.6 VS 2015 July 2015 initializers for automatically implemented properties, using directives to import static members, exception filters, indexed members and element initializers, await in catch and finally, extension Add methods in collection initializers.
C# 7.0 .Net 4.7 VS 2017 March 2017 tuples, ref locals and ref return, pattern matching (including pattern-based switch statements), inline out parameter declarations, local functions, binary literals, digit separators, and arbitrary async returns
C# 7.1 .Net 4.7 VS 2017 (v15.3) August 2017 async main, tuple member name inference, default expression, pattern matching with generics
C# 7.2 .Net 4.7 VS 2017 (v15.5) November 2017 private protected access modifier, Span, aka interior pointer, aka stackonly struct, everything else

Note: The language, framework as well as CLR are versioned independently.