tensile crack or simply a crack; if a displacement develops tangentially, it is called a shear crack, slip band, or dislocation.

Brittle fractures occur without any apparent deformation before fracture. Ductile fractures occur after visible deformation. Fracture strength, or breaking strength, is the stress when a specimen fails or fractures. The detailed understanding of how a fracture occurs and develops in materials is the object of fracture mechanics.