​​Does it belong in the application or domain layer?
If you're one of those people who make a separation between an application and a domain layer in their code base (like I do), then a question you'll often have is: does this service go in the application or in the domain layer? It sometimes makes you wonder if the distinction between these layers is superficial after all. I'm not going to write again about what the layers mean, but here is how I decide if a service goes into Application or Domain