Which muscles do pull-ups work?

Being able to do a pull-up is a common fitness goal but which muscles do pull-ups work and why are they so difficult?

Pull Up vs. Chin Up Which One Is Better For You?

The Complete Guide To Pull-up » 12 Best Pull-up Variations

Neutral Grip Pull-Ups - How To Do, Benefits & Muscles Worked

How to Train Your Chest with Pull Ups

What Muscles Do Pull Ups Work?

Which Muscles Do Calisthenics Exercises Work? - Gravity Fitness Equipment

Which Muscles Are Used During Pull Ups?

All About Pull-Ups: Muscles worked, benefits & how to start?

Which muscles are targeted by pull-ups/chin-ups? - Quora