When lines are connected into enclosed shape then this type of data termed as polygon data. Polygon should be closed. The start and end point should have the same coordinates. Examples of vector polygon feature are school boundary, city or any political line.
Both line and point feature data represent polygon data at a much smaller scale. They help reduce clutter by simplifying data locations. As the features are zoomed in, the point location of a school is more realistically represented by a series of building footprints showing the physical location of the campus. Line features of a street centerline file only represent the physical location of the street. If a higher degree of spatial resolution is needed, a street curbwidth file would be used to show the width of the road as well as any features such as medians and right-of-ways (or sidewalks).