What is /etc/passwd group shadow file in Linux

Passwd is a file where information related to the user is stored such as name, user id, group id,gecos field, home directory, and command shell it is in human-readable format

group is the file in a human-readable file where information related to which user account belongs to which group is stored

shadow is a file where encrypted passwords of the user account are stored

Formate of passwd is unique to another file

Username: Is the name of the account

Password: In the /etc/passwd file, the password field usually contains an encrypted password or a special value such as "x" or "*" indicating that the password is stored in the /etc/shadow file. The /etc/shadow file, accessible only to the system administrator (root), contains the actual encrypted passwords.

User id (UID): Unix-like operating systems identify a user by a value called a user identifier. and it is in a number

0 UID belongs to the Root account which has full control over the system

1–99: these UID are predefined accounts