The default method is to specify three points. The various methods are selected by following the prompts. This command is used to construct ellipses. There are other options explained in the AutoCAD reference manual. This command is used to draw what are known as polylines.
Individual segments can even have tapering thickness.
Thick segments are bevelled at intersection points. Polylines can be closed to form a polygon. To construct a polyline, simply follow the prompts. Most options are quite clear. Polylines are very important in AutoCAD because they are treated as single entities for many operations.