What is the primary purpose of a rocket's fins?

The primary purpose of a rocket's fins is to provide stability during flight and control direction. Fins are aerodynamic surfaces that help ensure the rocket maintains a straight path and doesn't tumble or spin uncontrollably as it ascends. When the rocket is in motion, the airflow around the fins generates a stabilizing effect, much like the way a rudder works on an airplane. This stability is crucial for the rocket to reach its intended altitude and trajectory, making fins a vital component of rocket design.

Fins do not primarily serve aesthetic purposes, nor are they designed to store fuel or reduce weight. Their functional role focuses entirely on maintaining the rocket's aerodynamic integrity during flight.