Stand tall with a barbell resting across your upper traps and not on your neck. Grip the bar with your hands comfortably wider than shoulder width. Feet should be shoulder width with the heel of each foot resting on top of a small plate (or equivalent platform). Brace your core and keep your chest up. Bending at the knees, drive your hips back and down as if you are going to sit on a chair. Lower slowly with control until your thighs are parallel to the floor or deeper depending on your range, making sure your knees are pointing in the same direction as your feet and that your lower back doesn't collapse. Inhaling throughout this lowering phase. Pause at the bottom, then push through your feet to extend your legs and drive your hips forward to return to the start position, exhaling as you do so. Do not lock out your knees at the top.