ICD stands for International Classification of Diseases. It is a system for doctors to use when diagnosing people with illnesses and injuries. When a doctor goes to treat someone, they use ICD to figure out what kind of illness or injury the patient has. ICD helps doctors by giving them a list of all the possible illnesses that the person might have so that the doctor can pick the right one. It also gives them a way to describe the patient's condition and to report it to other doctors or to insurance companies.