A crop view focuses on a portion of a drawing view by hiding all but a defined area. The uncropped portion is enclosed using a sketch, usually a spline or other closed contour.
You can crop any drawing view except a Detail View or a view from which a Detail View has been created. Crop View can save steps because you do not create a new view. For example, instead of creating a Section View and then a Detail View, then hiding the unnecessary Section View, you can crop the Section View directly.