A line, the most basic object, can be one segment or a series of connected segments.
In a simple line with connected segments, each segment is a separate line object.
A polyline is a connected sequence of line segments created as a single object. You can create straight line segments, arc segments, or a combination of the two.
You can create rectangles and regular polygons quickly. Creating polygons is a simple way to draw equilateral triangles, squares, pentagons, hexagons, and so on.
Multilines are composed of 1 to 16 parallel lines, called elements.
Sketching is useful for creating irregular boundaries or for tracing with a digitizer.