Shoulder press form

I see a lot of people doing this movement wrong. Whether you're standing or sitting down, the basic movement is to press the bar vertically and when the bar clears your head you crane your neck and head forward and the bar changes to arcing backward so when you're at the top of the lift the bar and your hands and arms are slightly behind the vertical plane of your torso. This prevents arching of the lower back which could result in lower spine injury.