Medical clinics can choose to operate on a walk-in basis or by appointment only. Some clinics will choose to operate both, with walk-in patients seen either between appointments or by a doctor designated to walk-in patients. Walk-in patients are seen in the order they arrive at the clinic, with them having to wait in a waiting room from a few minutes to a few hours, depending on how busy the clinic is. By booking an appointment, patients are guaranteed to be seen by a doctor at, or close to, a specified time. This will reduce the amount of time that the patient will need to wait for medical care, making it easier for them to plan their day.