The operating system must know who you are in order to provide you with the correct environment.
Passwords are a form of security.
People who know your login name cannot log in to your system unless they know your password. If your system is set up as a multiuser system, each authorized user will have an account, password, and login name on the system. The operating system keeps track of the resources used by each user. This is known as system accounting . Each user will be given a private area in the storage space of the system, called the file system .