I could write an entire book on the swing. There are very few movements as simple as the swing that have so many benefits accessible to so many people so quickly into learning it. Even better than the push up and the pull up (which I love), I can't think of anything that comes close to the total body benefit of the swing. I mean, a straight press (planche to handstand) will kick your ass, but there are only a handful of elite gymnasts that can pull it off. Anyone can swing a bell. It looks like this.
The key to the hard-style swing, and the thing that makes it so special, is that it is ballistic. You are throwing that bell as hard as you can with your hips then stopping the arch with your back and core. If you are doing it right, the weight doesn't even matter. The video above is of an RKC swinging a 60kg kettlebell. I didn't even know they made them that big. But he will get exhausted just as fast swinging an 8kg bell if he is doing it as hard as he can. That is because no matter what the weight, with every swing you are going balls out.
When you swing hard-style, the swing shows no mercy. When I started this whole kettlebell thing, I considered myself a conditioned athlete. I can run a 5k in 17:52 and a mile in under 5:15. But the swing taxes a completely different fuel system. The body stores energy as creatine triphosphate in the muscles so that when the ATP on hand is used up in 2-8 seconds, the muscles can still pump while they begin to break down muscle glycogen, then the glycogen in the bloodstream. This phasphogen system is rarely taxed unless you do a lot of combat sports like wrestling because most of the conditioning work that people do are less intense and do not need ATP faster than muscle glycolysis can provide it. But when you are forced to go as hard as you can and as fast as you can, the body relies on the phasphogen system to keep moving. Or in this case, swinging the bell.
The kettlebell swing is a form of pure exhaustion that hits you all over. Since you are using every major muscle group to both throw and stop the bell, and you are taxing that underutilized fuel system, the swing will bring any athlete to his or her knees. But these benefits are completely accessible to anyone with the mobility to swing. That is because as hard as it can be, the swing is also very finely throttled. If you get tired, you just swing a little less hard. It's not cheating if you can't actually swing any harder. It's just good strategy. The point is, there is no more simple, easily learned motion that people can benefit more from. And that's why it is one of the few exercises I do every day.