Final answer:
Student pilots, recreational pilots, and private pilots require a pilot's license to operate aircraft.
Step-by-step explanation:
Student pilots, recreational pilots, and private pilots (other than glider and balloon pilots) require a pilot's license to operate aircraft. Obtaining a pilot's license involves meeting age and medical requirements, completing flight training, and passing written and practical exams. Once licensed, pilots must also adhere to regulations and follow certain procedures for safe and legal operations.