modern field hospitals have changed from canvas tents to modern, well-equipped health care centers. while many are still made of fabric, they are specifically designed to be clean, safe and comfortable shelters. they are highly mobile and may be found in nearly all parts of the world. they range in size from small single room shelters to fully equipped hospitals with 200 or more beds. they provide all kinds of necessary medical care. modern field hospitals may have emergency rooms (er), intensive care unit (icu) and outpatient clinics. they provide all areas of needed health care from first aid to psychological care to preventive healthcare.