Line: An identifiable path created by a point moving in space.
Horizontal Line: A line that goes from left to right.
> The photo to the left is an example of horizontal line. The horizontal lines of the water and gravel running across the horizon causes the picture to have a feeling of rest and repose; objects parallel to the earth are at rest.
Vertical Line: A line that goes straight up and down.
> The photo to the right is an example of vertical line. The vertical lines of the bamboo give the photo a sense of height, for vertical lines are perpendicular to the earth.
Curved Line: A line that bends in a smooth, continuous way.
> The photo to the left is an example of curved line. The curved lines of the road naturally lead your eyes down the road. Curved lines can imply natural beauty.