Good form refers to precision of movement and involves:

1. Correct positioning BEFORE commencing the movement
2. Controlled action (that doesn’t use gravity or momentum to complete the movement)

Whether we’re talking about stretching, strengthening, weight-training or playing sport, good form is the most significant determinant of improving performance and avoiding injury. No amount of repetitions (reps) or sets of reps can compensate for executing an exercise or movement incorrectly.

Also see speed of movements