A strong, aesthetic back is a goal of everyone who lifts. But how to achieve it? I'm convinced that there is one exercise above all others that can help you get that back you're after. And that's the pull up. That's why I now do pull ups in every one of my workouts. Pull ups target your entire back -- the traps, the rear delts, the lats, and of course your biceps. By working all of these different muscle groups, pull ups are ideal for back development. Of course, pull ups are the hardest exercise I've ever learned how to perform. That's because you're pulling the entire weight of your body up against gravity. And you're having to recruit all of the muscles I've mentioned in order to do that. So by doing pull ups (rather than just pull downs) you're maximizing the time under tension that your back is experiencing.
I've started doing pull ups at the start of every workout because they require the most amount of effort and you're going to maximize mechanical tension. Of course, even if you can't do a bodyweight pull up yet, that doesn't mean you shouldn't incorporate pull ups into your workout routine. As I have said on numerous occasions, there's no shame whatsoever in using bands to assist you while doing your pull ups. Then it's just a matter of time before you're able to progress to the point where you're doing pull ups without any assistance. That's exactly what happened to me. Don't rush, try to control the movement, and really feel the muscles working. It's a blast!
Have a wonderful evening my friend!