WHAT IS A DROPSET?
A dropset is an older training method that goes wayback thats been used over time and time again by bodybuilders. During a droplet you would reach failure on your set of any exercises, then immediately decrease the weight and keep doing more reps until you reach failure again. This would be one dropset. The weight can be decreased repeatedly for multiple droplets in a single bout.
WHAT DOES A DROPSET DO?
It increases the intensity and volume for a targeted muscle group. This will force extra blood into the muscle. With your normal set you would reach 10 or 12 reps or however many it would take you to get to failure, then stop and rest. When you incorporate dropsets you are taking the muscle to failure and then past it, with more reps at a lighter weight. By doing that, you increase time under tension. More time under tension, with good recovery, good supplements, and good nutrition, will lead to more muscle growth and size.
HOW TO USE IT
I would say the best way to use a dropset is no more than two sets per body part. If you're drop setting one set, feel free to do two to three drops; If you are drop setting it on two sets, stick to one dropset each. One of the best ways to use dropsets is to use a machine so you can quickly remove the weight, or you can use dumbbells so you can quickly change the lbs your re using.
Dropsets are an advanced training technique, and if you are just starting on a fitness plan I would highly recommend to wait about 4-6 weeks to incorporate these into your routine. Make sure you always pay good attention to your form throughout your set when working the muscle to fatigue to prevent injury form bad form. These are an amazing way to get more gains in hypertrophy, muscle size and muscular endurance. These will also help you get through a training plateau.