
Circles are very popular and important. They serve as an enclosure or a central field. They are simplistic and perfect. A ring is a variation of the circle, and is used to show unity, eternity, wholeness, a cycle, and completion. The circle or sphere in the ATT logo is simple but appealing. It represents the globe and ATT's global presence. While its rings show unity and wholeness.

Squares are used as a filed for application. They show stability, structure, and secureness. They are very simple and welcoming- but not as welcoming as a circle. The Lego logo is very simplistic, but also shows complexity- because it is a product that is used to be put together. The square may also represent the lego blocks. It would not have made sense to make it a circle because there is no circular legos.