What is the difference between user and login in SQL Server?

How do logins differ from users?

A "Login" grants the principal entry into the SERVER. A "User" grants a login entry into a single DATABASE. One "Login" can be associated with many users (one per database).

What is SQL user without login?

The WITHOUT LOGIN clause creates a user that isn't mapped to a SQL Server login. It can connect to other databases as guest. Permissions can be assigned to this user without login and when the security context is changed to a user without login, the original users receives the permissions of the user without login.

What is a login in SQL Server?

A login is a security principal at the scope of the SQL Server instance, and a SQL Server instance can contain numerous databases. There are two main types of logins; Windows authenticated login and SQL Server authenticated login. Simply stated, a login allows you to connect to a SQL Server instance.

How do I login a SQL user?

Create a login using SSMS1In Object Explorer, expand the folder of the server instance in which you want to create the new login.2Right-click the Security folder, point to New, and select Login....3In the Login - New dialog box, on the General page, enter the name of a user in the Login name box.Create a Login - SQL Server | Microsoft Docs