Scaling functions allow you to change size along either axis, and can also result in reflection about the coordinate axes. Rotation changes the angle of rotation of a shape by the amount specified in the mapping, rotating all points around a given point. Skewing changes the slant applied to a shape by the amount specified in the mapping. Skewing functions allow you to apply slant along either coordinate axis, relative to a given point. The term shearing is synonymous with skewing.
Perspective modifies the positions of points to give a three-dimensional effect.
When you multiply two or more matrices to obtain a cumulative result, you concatenate, or accumulate the transformations of, both mappings. Matrix multiplication is not commutative. Multiple concatenations can occur in QuickDraw GX, such as when drawing picture shapes or when drawing any shape through a hierarchy of view ports. The motivation is speed. It is much faster to concatenate mappings than to apply a mapping to a large number of points.