the short answer
The deadlift is a hip-hinge pull where you lift a loaded barbell from the floor to a standing position. The single most important cue is to keep the bar close to your body and dragging up your legs the whole way - a bar that drifts forward shifts the load onto your lower back and breaks the lift down.
This article is general technique education for coaches and their clients, not medical or rehab advice - form is individual, so program within each person's capacity and get a qualified coach to give an in-person form check.