group
also: GID, group ID
A collection of user accounts that share common permissions and access rights to files and resources. Groups simplify management by allowing multiple users to be granted the same privileges at once.
In Linux, a group is a mechanism for organizing users and controlling access to files and directories. Every user belongs to at least one primary group, and can be a member of multiple secondary groups. Each file and directory has an associated group owner, separate from its user owner.
Groups are defined in the /etc/group file, which maps group names to numeric group IDs (GIDs). When you set file permissions, you can grant specific rights to the group owner, making it easy to give a set of users access without managing individual permissions for each person.
For example, if you have a developers group containing five engineers, you can set a project directory's group to developers and grant write permissions to the group. All five users then have write access automatically, without needing individual entries.
View your groups with groups, change a file's group with chgrp, or modify group membership with usermod -G.