An access group is a named set that pairs users with the doors, areas and schedules they are allowed to use. Adding a person to the group grants all of its permissions at once. Groups keep administration consistent, and the common pattern is one group per department, shift or job role.
Groups exist because permissions multiply quickly. Ten doors and twenty people could mean two hundred individual decisions, or a handful of groups that can each be reviewed in one place.
Why groups beat door lists
Assigning doors one person at a time is slow and easy to get wrong; a group states the permission once and applies it to everyone who belongs. When a door or a schedule changes, the group changes and every member follows, which keeps a large site’s rules from drifting apart.
Designing groups for a site
Start from how the building is used: a main entrance, a staff area, a server room and a loading dock probably need different sets. Name groups after the work rather than after individuals, and review membership when people change roles, so access does not accumulate over time.