If a set of forces acting on a body does not change the state of rest or of motion of an object such forces are called balanced forces. In this case object is said to be in equilibrium state. The vector sum of all forces is zero i.e. ∑Fx=0.
Set of forces acting on body results in change in state i.e. either changes the speed or direction, such forces are called unbalanced forces. In this case the object is in non-equilibrium state and the resultant force is non-zero. i.e. ∑Fx≠0.