Critical care is provided for patients who are suffering from life-threatening conditions. The doctors who work with these people are often called intensivists. They focus on a range of different issues, so they can serve people who need immediate and life-saving care. Since people who need critical care are suffering from such a wide variety of issues, intensivists must have a thorough understanding of diverse types of medical issues and the devices and medications needed to treat them.

Dermatologist is a doctor who has received special training to treat adults and children with benign and malignant disorders of the skin, hair, nails, and mucous membranes. They can diagnose skin cancer, skin allergies, and other skin conditions and disorders. They also treat these skin problems and look for underlying causes.

An internist or Internal Medicine doctor is someone who specializes in diagnosing and treating illnesses, diseases, and health problems. Most internists are also primary care doctors and treat patients on a regular basis. They can diagnose and treat common illnesses or more serious problems. Most people see an internist regularly. Those with chronic illnesses may do so on a monthly or even weekly basis. Internists are the most common types of doctors.