A broken or cracked bone is known as a fracture. Fractures can affect any bone in the body.
Bones can fracture in a number of different ways. A fracture may be a straight break across the bone (transverse fracture), slanting (oblique fracture) or winding (spiral fracture). The break may run along the shaft of the bone (longitudinal fracture), or the bone may be shattered into pieces (comminuted fracture).
Young bone is softer and more able to bend than adult bone, so children's bones often fracture on one side but bend on the other. This is known as a greenstick fracture.
An avulsion fracture is when a piece of bone detaches from the main bone, usually because of being torn away by the tendon that attaches a muscle to a bone. A fracture in which the bone collapses is called a compression fracture. Compression fractures usually affect the spongy bone found in the spine.
A fracture in which the skin around the bone has not been broken is called a simple or closed fracture. If the ends of the bone break through the skin, or there is a wound that leads to the fractured bone, it is called a compound or open fracture. In a compound fracture the bone is open to infection, so this type of fracture is more serious.
A complicated fracture is one in which there is injury to other nearby structures, such as major blood vessels and nerves. A fracture-dislocation occurs when a joint becomes dislocated and there is also a fracture of one of the bones of the joint.
After a fracture, the broken fragments of bone normally separate from each other. However, sometimes one fragment of bone can be driven into another. This is known as an impacted fracture.
Source: the information above comes from NHS Choices - visit the NHS Choices website for information about symptoms, causes and treatment of fractures.