.Net 7

This page covers the most important changes introduced in .Net 7 (in my view). For the full breakdown see the official documentation and Blog Post Features and Blog Post Performance.

New Features in .Net 7

Introduced JSON contracts to System.Text.Json which allow for more control over the serialization process.
Built-in Container support via dotnet publish
.NET library improvements:
- Support for microseconds and nanoseconds in TimeSpan, TimeOnly, DateTime, and DateTimeOffset types
- APIs for reading, writing, archiving, and extracting Tar archives
- Rate limiting APIs to protect a resource by keeping traffic at a safe level
- New type converters for DateOnly, TimeOnly, Int128, UInt128, and Half
- APIs to get and set Unix file permissions
- APIs to interop with JavaScript when running in the browser or other WebAssembly architectures
NET MAUI is now part of .NET 7

.NET 7 also brings with it a new version of the C# language. The most important changes are:

Support for static virtual members in interfaces
Pattern matching: List patterns. With list patterns you can apply patterns recursively to the individual elements of list-like input – or to a range of them.
Added the require modifier. Indicates that the field or property it's applied to must be initialized by an object initializer.
Introduced generic math operations, which allow you to perform mathematical operations generically—that is, without having to know the exact type you're working with (e.g. double/decimal/etc.)

With .NET 7 the performance on Arm64 has been improved. Many Micro benchmarks improved by 10~60%.
Native AOT produces a standalone executable in the target platform's file format with no external dependencies. It's entirely native, with no IL or JIT, and provides fast startup time and a small, self-contained deployment. In .NET 7, Native AOT focuses on console apps and requires apps to be trimmed.
and many more improvements (see the blog post)