groupThe group file is as like passwd file. passwd is used to store user account information as like group file is used to store group information. It is located at /etc/group. It mainly used for store group name and their user name. Normal user can view this file. But only the root user can edit this.
Location : /etc/group
1 - GroupName : It is name of group.
2 - Password : Normally password is not used in group. It can store encrypted password as like shadow, here it'll be in gshadow. This is useful to implement privileged groups.
3 - GroupId (GID) : It is a unique id for the group. Each user have group id. We can see this at /etc/passwd file.
4 - Group List: This is list of user under this group, means member of this group. Each user separated by comma",".
* Use man pages for more help.