Reps= the amount of times you do a certain exercise or movement.
For endurance lifting or the "sleek" look, 12-15 reps is ideal
For strength lifting or "size/bulk", 6-10 with SUPER HEAVY weights
***DISCLAIMER**** Women who want a toned body should be lifting heavy...YOU WILL NOT BULK UP! You don't have the testosterone to do so!
Sets= group of repetitions performed for different exercise
for most 1-3 sets is ideal depending on your goals and what you are doing!
So MANY sets so little time...
What they are: The usual—a number of repetitions followed by a rest period, then by one or more sets of the same exercise.
Why they're useful: The rest periods and narrow focus of straight sets help add mass and build maximal strength. As long as you rest enough between sets (1 to 3 minutes), your muscle, or group of muscles, will work hard two, three, even five times in a workout.
How to use them: The start of your workout is the best time to do straight sets, regardless of your experience level, Ballantyne says. Your energy and focus are high at the start, so it's the best time to execute difficult moves. Perform three straight sets of six to eight repetitions of a challenging exercise like the bench press, pullup, or squat; aim to do the same number of repetitions in each set, with either the same or increasing amounts of weight.
What they are: A set of each of two different exercises performed back-to-back, without rest.
Why they're useful: Supersets save time and burn fat. You can multitask your muscles—for instance, working your chest and back in one superset and legs and shoulders in another. Lifting heavy weights in a short time period increases the rate at which your body breaks down and rebuilds protein. This metabolism boost lasts for hours after you've finished lifting.
How to use them: Insert a superset at any time in your workout. To involve the most muscles, pair compound exercises—moves that work multiple muscles across multiple joints. For example, combine a chest press with a row, or a shoulder press with a deadlift. To save more time, pair noncompeting muscle groups, such as your deltoids and glutes. One muscle group is able to recover while the other works, so you can repeat the set without resting as long.
What they are: Three different exercises performed one after another, without any rest in between.
Why they're useful: Trisets save time and raise metabolism. A single triset can be a total-body workout in itself, like our 15-minute workouts.
How to use them: Trisets are a good workout for at home (or in an empty gym), because you need to monopolize equipment for three exercises.
What they are: Three or four sets of one exercise performed without rest, using a lighter weight for each successive set. Also called descending sets or strip sets.
Why they're useful: Drop sets are a great quick workout, fatiguing your muscles in a short time, getting your heart going, and giving you an impressive postworkout pump as your muscles fill with blood.
How to use them: Use drop sets when you're pressed for time. Don't do them more than three times a week; you'll get so tired you won't be able to accomplish much else. Start with a warmup, using 50 percent of the weight you expect to use in your first set. Now use the heaviest weight you'd use for eight repetitions of that exercise to perform as many repetitions as you can. Drop 10 to 20 percent of the weight and go again. Continue to reduce the weight and go again, always trying to complete the same number of repetitions (even though you won't), until your muscles fail.
What they are: A series of exercises (usually six) that you complete one after another without rest, though you can do some cardiovascular work (such as jumping rope) between exercises.
Why they're useful: When you use weights, circuits can be a great total-body workout. But they're most valuable without weights as a warmup of the nervous system, joints, and muscles, Ballantyne says. Because a circuit stresses the entire body, it's more effective than a treadmill jog, which primes only your lower body.
(Men's Health Magazine)
Now that you understand that you can decide what works best for you!