Each .NET version is released with some significant improvements:
.NET 1.0 - 2002 Initial version(1st release)
.NET 1.1 - 2003 Update on 1.0, add provider for oracle
.NET 2.0 - 2005 Generics were introduced.
.NET 3.0 - 2006 WPF, WCF, WF were introduced.
.NET 3.5 - 2007 LINQ and ADO.NET Entity Framework
.NET 4.0 - 2010 Dynamic support for languages and TPL(Dynamic keyword introduced along with Task Parallel Library)
.NET 4.5 - 2012 Asynchronous programming support(async and await keyword introduced).
.NET 4.6 - 2015 It supports a new just-in-time compiler (JIT) for 64-bit systems called RyuJIT, which features higher performance and support for SSE2 and AVX2 instruction sets.
.NET 4.7 - 2017 Enhanced cryptography with elliptic curve cryptography, Improve TLS support, especially for version 1.2 .
.NET 4.8 - 2019 It includes additional enhancements for high-resolution displays, performance updates, and security enhancements.