Diagonal lines convey instability tension and action.
Diagonal lines are unbalanced. They are filled with restless and uncontrolled energy. They can appear to be either rising or falling and convey action and motion. Their kinetic energy and apparent movement create tension and excitement. Diagonal lines are more dramatic than either horizontal or vertical lines.
Diagonal lines can also appear solid and unmoving if they are holding something up or at rest against a vertical line or plane.
Lines are everywhere. You can see lines in the grain of a piece of wood or in the cracks on a sidewalk. Lines are used to create words, numbers, and symbols. They are also used to create art. In drawing, line is an element of art that is the path of a moving point through space.
Aside from diagonal lines, other basic kinds of lines include: vertical, horizontal, curved and zigzag. Learn more about these lines from links below:
hebebrandgpaart.wikispaces.com
www.apelslice.com
vanseodesign.com