C# haven't static variables at all. You can declare static field in the particular type definition via C#. Static field is a state, shared with all instances of particular type. Hence, the scope of the static field is entire type. That's why you can't declare static field within a method - method is a scope itself, and items declared in a method must be inaccessible over the method's border.

C# doesn't support static local variables (that is, variables that are declared in method scope).

https://learn.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/static-classes-and-static-class-members#static-members

You can declare static fields (class members) though.

Reasoning: Static field is a state, shared with all instances of particular type. Hence, the scope of the static field is entire type. That's why you can't declare static instance variable (within a method) - method is a scope itself, and items declared in a method must be inaccessible over the method's border.