A grid used for page layout that is the same on both the recto and verso pages. Asymmetric grids typically introduce a bias towards one side of the page, usually the left, as pictured above. The additional margin space can be used for notes and captions.
If you understand symmetry then you are on your way to understanding asymmetry. Asymmetry exists when the two halves of something do not match or are unequal. The American flag is an example of asymmetry.
Asymmetry is the absence of, or a violation of symmetry (the property of an object being invariant to a transformation, such as reflection). Symmetry is an important property of both physical and abstract systems and it may be displayed in precise terms or in more aesthetic terms. The absence of violation symmetry that are either expected or desired can have important consequences for a system.