Barbell Squat.

High-bar squat: the bar rests on the upper trapezius, across the top of the muscle shelf below the neck. To find it, squeeze your shoulder blades together, reach your hands in toward your shoulders, and the trap muscles will bunch up into a natural rack. The bar should feel stable there without pressing on the spine itself. Low-bar squat, which is a separate variation, sits a few inches lower across the rear deltoids and requires a more horizontal torso to stay balanced. Most lifters and most general programs use high-bar. Powerlifters often favor low-bar for a mechanical advantage at maximal loads.

Almost always ankle mobility, specifically limited dorsiflexion. When the ankle can't flex far enough to keep the heel down as you descend, the heel rises to compensate. A short-term fix is squatting with 5 lb plates under your heels; this reduces the dorsiflexion demand and lets you practice depth. The long-term fix is daily ankle stretching: calf raises, banded ankle mobilizations, and deep squat holds. Some people also have structural limits (hip socket shape) that make a truly upright torso and flat heels impossible simultaneously. A slightly wider stance often solves this.

A belt is a tool, not a crutch. It gives the core something to brace against, which lets most lifters produce slightly more intra-abdominal pressure and move more weight safely at higher intensities. It doesn't replace core strength. It augments the brace you're already creating. Most coaches recommend training without a belt for submaximal work (below 80-85% of your max) so you build core strength that transfers. Use a belt for heavy top sets, max attempts, and singles. Don't use it for warm-up sets or technique work.

The standard target is just below parallel, meaning the hip crease drops just below the top of the knee at the bottom. Most strength programs and all powerlifting federations define a legal squat this way. Going deeper is fine if mobility allows and the spine stays neutral. A full Olympic-style squat with the thighs past parallel is a valid and effective variation. The mistake is chasing depth at the expense of a neutral spine: if your lower back rounds aggressively at the bottom, your range of motion exceeds your current mobility and you should stop there and work to improve it over time.