It is extremely important to use proper form and practice the correct technique when exercising. For fitness veterans this seems like a no-brainer but many beginners are lost when it comes to this subject. The number one reason why it is so important, is to avoid injuries. Using improper form and technique can lead to injuries that will slow down or completely stop your progression.
Form is also important in making sure you are using the correct muscle in connection with the exercise you are doing. If you are curling dumbbells to work the biceps but use your back to swing the weights up, you might be dissatisfied with the results. You may also cause harm to your lower back. The correct form will allow you to increase strength and muscle tone while avoiding injuries.