- The circle is protective or infinite.
- The square denotes stability, equality, and honesty.
- The triangle suggests tension or conflict or action.
There are so many things you can draw using only circles, squares, or triangles. Group several together to form interesting patterns. You can make one shape from another — such as the group of circles that form a triangle,in the illustration.
Alternating direction or color, disrupting a pattern with another shape or a shape out of alignment can add interest or suggest abstract ideas. A triangle alone or a series of overlapping ones can "point" in one or more directions.
Replace letters in a wordmark or name with shapes that suggest those letters. A triangle for A or V is obvious. Less obvious is the E made of squares (in illustration) or perhaps two stacked circles for an S or a pair of triangles (one up, one down) for an N. Extending the concept slightly, the red ball (a circle) replaces the first o in the About.com logo.
Logo designs don't need to be elaborate — and usually work best when they are kept simple. So simple shapes work beautifully.