The sounds produced by joints are a common source of questioning for doctors and their patients. Two major types are identified : cracks and crepitus. Few investigations have been carried out on these manifestations, while they potentially have clinical implications, especially for patellar crepitus in patellofemoral osteoarthrosis, and may generate anxiety. Knuckle cracking appears to be caused by the sudden and temporary occurrence of an intra-articular gaseous cavity, called tribonucleation. Other researches on these sounds are focused on the knees and their links with osteoarthritis, as well as on the spine. Many questions still arise but it seems important to talk about it with patients without trivializing them.