How do lines differ in a drawing?

A drawn line can suggest the edge of a roof, a road or the bend of a river. It is a mark that follows a path. One useful question is whether that path stays straight or curves as it goes.

A straight line can run across the page, up and down, or on a slant. A sloping roof edge can be straight even though it is not level. Direction describes which way the mark runs; straightness describes whether its path bends.

A curved line changes direction along its path, as a winding-river drawing does. Artists can combine straight and curved marks to describe different edges and outlines. Turning a straight mark on the page changes its direction without making it curved. These separate features help simple lines become the recognizable parts of a drawing.