Disclosed are a laundry treating apparatus, a laundry treating system, and a method of controlling the laundry treating system. The laundry treating system includes a laundry treating apparatus configured to perform a course for treatment of laundry through rotation of an accommodation part and an external device configured to determine a personalized course based on information provided by a user to determine a course group. The laundry treating apparatus stores the course group transmitted from the external device and provides courses included in the course group to the user to allow the user to select the courses.