Used to summarize "who's involved" at a glance — a document's co-editors, a call's participants, a task's assignees. The "Avatar" entry elsewhere in this dictionary covers a single avatar and its photo-load fallback, while this one focuses on the composition pattern of arranging several avatars as one unit.
Overlapping circles leave no room for a visible name, so each avatar's accessible name needs to come from title or aria-label rather than visible text. A hover tooltip is enough on its own for mouse users, but touch devices have no hover, so the "+2" overflow button should also open a full list of names.
Picking a consistent rule for ordering — say, the most recently joined person goes first (or last) — makes positions feel stable rather than shuffling differently every time.