A whole team working on one Revit model at once. The terms every junior hears in week one on a real project. Worksharing is Revit's mode for letting a whole team work on one model at the same time: the project lives in a Central Model (on a server or in the cloud), each person works on a synced local copy, and changes flow back with "Synchronize with Central". Worksets split the model into logical chunks - shell, interiors, site - so ownership and visibility can be managed per team. If you ever wondered why file names end with "_Central" - this is why.