A cross section is an imaginary cutting plane applied through a part, with a cross hatch pattern associated with it. How the cross section is shown in a particular view is a function of that view's view type- full, half, local, etc.

Before placing a cross section defined as planar in the view, you must orient the view so that the plane of the section is parallel to the plane of the screen. If the cross section is revolved, the plane of the section must be perpendicular to the screen.

You can create cross sections in part and assembly mode, which can be used to display portions of the component within drawings. These three-dimensional cross sections are similar to assembly cuts, but are only used for display purposes.