Urgent care is a category of walk-in clinic focused on the delivery of ambulatory care in a dedicated medical facility outside of a traditional emergency room. Urgent care centers primarily treat  injuries or illnesses  requiring immediate care, but not serious enough to require an ER visit. Urgent care centers are distinguished from similar ambulatory healthcare centers such as emergency departments and convenient care clinics by their scope of conditions treated and available facilities on-site. While urgent care centers are usually not open 24-hours a day, 70% of centers in the United States open by 8:00 am or earlier and 95 lose after 7:00 pm.