The Squat - Ron Morris

Just his opinion: 

The Unholy Trinity

1. The Kettlebell Swing
2. The Pushup
3. The Squat.

Interesting perspective.

I do like the Squat description but let's break it down, sentence by sentence.

1.) The squat is about flexibility and strength, and when done correctly, works cardio as well. To begin, stand straight, not slouched, feet 1-2 inches beyond shoulder width.
2.) All attention begins at Hanzo, head and gaze level, shoulders down.
3.) As you descend, your hips should be going straight back, sitting back, not down.
4.) Continue to lower yourself, your torso remains straight up and down, don't lean over your feet or knees (thighs should be behind your knees). 
5.) Go to parallel, which means, top of thighs parallel with floor, hip bone below knees. 
6.) Don't hold your breath, breathe all the way down, evenly.
7.) Don't bounce or drop quickly, the slower the better. 
8.) A brief pause, then rise, shoulders back, head up. 
9.) This is usually the part where everybody tries the shortcut, racing back up will put your body out of alignment.
10.) Smooth and strict-keep your attention on Hanzo, exhale breathe on the top.

Possibly something like this from a Men's health illustration.

Looks like Jump Squats and Barbell Squats are interesting variants.