Symmetry is an age-old device of the visual artist. The word refers to two halves that perfectly mirror each other. In design, symmetry is closely tied to balance. A perfectly symmetrical web design achieves balance and a sense of stability.
Most often we find the logo in the top left, balanced by some navigational elements on the right. In the body, the side columns are usually balanced by either the main content or other columns. Here are some stunning examples of symmetry related websites for new web developers.