What the difference between extension and hyper extension?

Extension and hyperextension are terms used to describe movements in joints. Extension refers to the straightening of a joint, increasing the angle between body parts, such as straightening the elbow or knee. Hyperextension occurs when a joint is extended beyond its normal range of motion, resulting in an angle greater than 180 degrees, which can sometimes lead to injury. Essentially, while all hyperextension is a form of extension, not all extension qualifies as hyperextension.