Deformation mechanisms refer to the means by which materials change their shape and size in response to loads. Fracturing is one of these mechanisms, which is the discontinuous deformation of solids. The science of fracture mechanics helps us understand and rationalize the mechanisms of various types of fractures through the laws of physics and mechanics. We first give separate overviews of these subjects. However, because it is not always practical to separate mechanisms and mechanics of fractures from each other, we present them together when we consider individual fundamental structure elements, structural associations, and development stages.