A Revit view type showing an enlarged, cropped portion of another view - used for detail drawings that zoom into a small area without duplicating the whole plan or section. A callout stays linked to its parent view - move a wall in the plan, and the callout's cropped detail view updates with it - which is what makes it the right tool for a wall-section detail or a stair detail, instead of drafting a disconnected duplicate view that would silently go out of sync.