AiAF

AiAF stands for Artificial Intelligence Auto Focus. It is a system devised by Canon that assists a digital camera in obtaining a focus automatically. It selects a focus point from a set of 3, 5, or 9 (depending on camera model) based on factors such as motion and subject position. AiAF is available in 3, 5, and 9 point options. The levels correspond to the number of different points the AiAF has to work with. The higher the points, the more accurate the focus.

External link

Canon's Website