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?

Close Grip Pull-ups: Benefits, Muscles Worked, and More - Inspire US

Which Muscles Do Calisthenics Exercises Work? - Gravity Fitness Equipment

Do Pull-Ups & Push-Ups Work Every Muscle in the Upper Body

How to Do Pull-Ups: Muscles Worked & Proper Form – StrengthLog

How To Do A Pull-Up Muscles Worked And Benefits

What Muscles Do Pull Ups Work?

What Muscles Do Pull Ups Work: Explaining Bodybuilding Properly

Do Pull Ups Work Chest? Or Is This Back Only?

Pull-Up muscles - Which muscles are used during Pull-Ups?

Which muscles group does pull ups grow? - Quora

Pull-Up vs. Chin-Up: Differences, Technique, and Variations