C# 9.0 introduces record types, which are a reference type that provides synthesized methods to provide value semantics for equality. Records are immutable by default. Record types make it easy to create immutable reference types in .NET. C# forced you to write quite a bit of extra code to create immutable reference types. Records provide a type declaration for an immutable reference type that uses value semantics for equality.
In this video, I show you what we need to do prior to C# 9 in order to get similar functionality and then introduce C# 9 Record types, so that you can truly appreciate this new feature.