Urgent care is the delivery of ambulatory care in a facility dedicated to the delivery of medical care outside of a hospital emergency department, usually on an unscheduled, walk-in basis. Urgent Care Centers are primarily used to treat patients who have an injury or illness that requires immediate care but is not serious enough to warrant a visit to an emergency department. Often Urgent Care Centers are not open on a continuous basis, unlike a hospital emergency department which would be open at all times.