What is a group?

Groups are an additional primitive that allows a set of users to share permissions. Groups are often used to get the functionality of a permission set or profile. For example, on Linux, there’s often a group called sudoers, and on macOS, you’ll encounter a group called wheel. By convention, users who are members of the sudoers or wheel groups on these systems are allowed to use sudo to execute commands as root. This is functionally the same thing as adding a user to the Administrators group in Windows.

You can extrapolate that if groups are useful for managing who is allowed to run the sudo command, they might be useful for grouping together users and managing other kinds of permissions, too.