I've been trying to find why, how and where to use Users Without Login and I didn't find my exact question or anything that gets closer. Where I did my research (I also read other posts, saw Youtube Videos):
I was searching for ways to turn my db more secure and I recently came to know that there's an option to create user without login. I thought it is nice. But I didn't understand how to use it (not create, use), then after my research I realized that this user accesses the db while impersonating another user/role. I thought it would be great to not have a user and somehow access the db. But when I saw that there's something called execute as I thought that it wasn't useful because why I would execute queries on this "login-less" user as it was another user? Why I just don't use this user's permission? Then I thought maybe this user has too much permissions, so I just create a new one with less permissions...
Okay, I don't know why you would create a user without login. How should this be used? It's stupid, but I tried to login and failed (sorry, but I'm used to login with users, I never thought on creating a user and not to login, I just know that users login to something, that's where my knowledge is).
So, I don't know why to create this type of user instead of a normal one? I don't know how (like do I login, do I just type the query and to use it)? I don't know where (like, do I need to make an C# app, do I use command...) to use?
My knowledge only takes me till here, I don't have a Senior DBA to ask. Please explain in simple words if possible.