In geometry, a rectilinear figure can be defined as a plane figure or shape all of whose sides meet at right angles. The interior angle at each vertex of a rectilinear is 90 degrees (90°) or 270 degrees (270°). Here, for instance, are a few irregular polygons that classify as rectilinear figures.
A polygon is a simple closed rectilinear figure i.e. a polygon is a simple closed plane figure made up entirely of line segments. Thus, every polygon is a rectilinear figure but every rectilinear figure is not a polygon.
The importance of the class of rectilinear polygons comes from the following. They are convenient for the representation of shapes in integrated circuit mask layouts due to their simplicity for design and manufacturing. Many manufactured objects result in orthogonal polygons.