Why do your knee hurt when it crack and pop?

Knee cracking and popping sounds, known as crepitus, can occur due to various reasons, including the movement of tendons or ligaments over the bones or the release of gas bubbles in the joint fluid. While often harmless, these sounds can sometimes indicate underlying issues, such as cartilage wear or joint inflammation. If accompanied by pain, swelling, or decreased mobility, it's advisable to consult a healthcare professional for an accurate diagnosis and appropriate treatment.