A table view in Revit that lists model elements and their parameters as rows and columns - a door schedule, a room finish schedule, a window schedule - built directly from live model data rather than typed in by hand. Because a Schedule is really just another view of the model, editing a value in the schedule changes the actual element, and editing the element updates the schedule instantly; the two are never out of sync the way a model and a separately-maintained spreadsheet always eventually are.

Schedules are also the most common practical output of QTO: a material takeoff schedule with a calculated quantity column is often the fastest way to get numbers out of a model and onto a cost plan.