Converging lines can be a powerful type of visual pathway. Multiple lines can all point towards your subject, or radiate out from it if you start tracing them in the other direction. Converging lines, such as lines of perspective, make for powerful compositions.
Linear perspective involves both line and depth. Converging lines, such as in architecture, show linear perspective. This kind of perspective also exists in exterior formations, such as roads and buildings. Perspective is very powerful in developing the illusion of space.
Perspective creates strong, obvious lines that can be used to align the other elements of the composition. This is effective when the subject is placed either at the vanishing point or at the point of greatest divergence. If the vanishing point is within the frame, the eye is drawn to it. In the case that the vanishing point is out of the frame, the viewer will tend to be drawn to whichever vertical line, closest to the camera, joins the lines of perspective.
Undulating curves include S-shaped, Z-shaped, and zigzagging lines, whether they be curved or jagged. The image below is an example of this in nude composition
The above is an excerpt from Exquisite Curves