What are the marker types for assemblies in .NET?

Question

What are the marker types for assemblies in .NET?

I am learning the AutoMapper through the tutorials and I come across the concept of the marker types for assemblies over here :

// Or marker types for assemblies:
var configuration = new MapperConfiguration(cfg =>
    cfg.AddMaps(new [] {
        typeof(HomeController),
        typeof(Entity)
    });
);

While searching for the answer to my question I come over this SO question. But I was not able to find the answer there.

Answer 1

I guess, that in scope of AutoMapper and your sample

// Or marker types for assemblies:
var configuration = new MapperConfiguration(cfg =>
    cfg.AddMaps(new [] {
        typeof(HomeController),
        typeof(Entity)
    });
);

it means any type from the particular assembly, which is used to "mark" the assembly for scanning for mapping profiles. Assemblies containing HomeController and Entity types will be scanned for getting a types inheriting from Profile for mapper configuration

AutoMapper will scan the designated assemblies for classes inheriting from Profile and add them to the configuration