Pull-Up

Trains the Lats.

How to do it

Take an overhand grip on a bar, hands slightly wider than your shoulders. Wrap your thumbs around the bar.
Hang with your arms straight and let your shoulders rise toward your ears. This is a full hang and it is the starting position — the lats are at their longest here.
Before pulling, draw your shoulder blades down and back, as if putting them in your back pockets. The bar has not moved yet and you should already feel your upper back working.
Pull by driving your elbows down and back toward your ribs rather than by pulling with your hands. Your arms are hooks; the movement comes from the back.
Keep your body still — no swinging, no kicking. Squeezing your glutes and bracing your stomach stops the legs contributing.
Pull until your chin clears the bar, then lower under control all the way back to a full hang. Stopping short at the bottom removes the part of the range where the lats are stretched under load, which is the part worth having.

Not going all the way down. A half-range pull-up avoids the bottom of the movement, which is exactly where the latissimus dorsi is longest and doing the most. Full extension every repetition, even if it means fewer of them.
Pulling with the arms. Because every pulling movement bends the elbow, the biceps will happily take over the whole set and the back will feel nothing. Thinking about driving the elbows down toward the hips rather than pulling the chin up is the standard fix.
Swinging or kipping to get up. That is a different exercise with a different purpose, and if the goal is training the lats it removes most of the work. Band assistance or a lat pulldown at a manageable load builds the strength honestly.
Shrugging at the top. If the shoulders travel up toward the ears at the end of the pull, the upper traps have taken over from the lats. Keeping the shoulder blades pulled down throughout is what keeps the work where it belongs.