Anyone who has any sort of procedure done without being admitted to the hospital is seen as outpatient. There are a lot of simple medical procedures that can be done as outpatient. If you go into the hospital to have a surgery done where you do not have to be admitted into the hospital to stay overnight you are considered outpatient.
You are also considered outpatient if your doctor sends you to the hospital for x-rays or other diagnostic tests only. Another way that you might be considered outpatient is if you go into the emergency room for something and are treated but not admitted into the hospital.