There are two kinds of control surface balance, aerodynamic and mass.

Aerodynamic balance is achieved when the pivot runs through the aerodynamic center of the movable surface. This kind of balance reduces the net torque on the surface to zero.

Mass balancing increases the period of oscillation to infinity which is the equivalent of reducing the frequency to zero.

If either type of balance is perfect, it is completely effective in supressing the associated mode of flutter.

In addition to the flutter mode of flapping around the pivot line there are several possible aeroelastic modes of flutter. There can be longitudinal flutter along the span and torsional flutter along the span as well as others.