While many minor ailments can be treated with rest and fluids or a visit to the primary care physician, when a more serious sickness arises, a physician with specialised training and experience may be required. Examining patients, gathering medical histories, conducting tests to aid determine a diagnosis, and prescribing drugs are all critical activities shared by all physicians. They may advise patients on healthy practises and how to stay healthy. Some clinicians, for example, specialise in diagnosing and treating disorders in a certain organ or area of the body, a type of condition, or a technique of treatment. Allergists and immunologists specialise on allergic and immune-related illnesses. Dermatologists assist individuals suffering from skin disorders. Neurologists are experts in nerve system diseases and disorders. Pathologists investigate the causes and characteristics of diseases. Radiologists diagnose disease using X-rays and radioactive materials. Sports medicine doctors help players avoid injuries and treat those that occur during sporting activities and training. Physicians and surgeons frequently work long and difficult workweeks. Unlike in primary care, patients seen by these specialists have already been referred due to their symptoms, hence they are frequently sicker and have more serious illnesses. Doctors and surgeons have received considerable education and training. Physicians receive a medical degree after completing a bachelor's degree, which normally takes four years, followed by three to seven years of internship and residency programmes, depending on the speciality.