What is posture? A clear definition, and what good vs. bad looks like
Posture is the position your body holds while sitting, standing, or moving — specifically, how your head, spine, and shoulders line up relative to each other. "Good" posture means your head sits roughly stacked over your spine with your natural back curves intact; "bad" posture means that alignment has drifted, most commonly as a forward head, rounded shoulders, and a flattened or over-curved lower back from long periods sitting at a desk.
force on your cervical spine when your head tilts 60° forward — vs. ~5 kg upright
people worldwide live with low back pain, per the World Health Organization
Good posture vs. bad posture, in practice
At a desk, the difference is usually visible from the side. Good posture: ears roughly above shoulders, shoulders relaxed and down (not rolled forward), lower back keeping its natural slight inward curve, feet flat on the floor. Bad posture: the head has crept forward of the shoulders, the upper back has rounded to compensate, and the lower back has either flattened out or collapsed into a slump as the body sinks into the chair over the course of an hour.
Why it matters beyond just looking better
Posture isn't a cosmetic habit — it determines how much load your spine and muscles carry for hours at a time. The further your head tilts forward, the more force your neck and upper spine have to support just to hold it up, which is the direct mechanism behind the neck and shoulder tension most desk workers eventually get. Over years, the same pattern is a contributing factor in the kind of chronic low back pain that the World Health Organization lists as the single leading cause of disability worldwide.
Why it's hard to maintain on your own
Nobody decides to slouch. It happens gradually — one degree of forward lean at a time, over the course of an hour of focused work — which is exactly why it's so hard to catch yourself doing it. By the time you notice tension in your neck or an ache in your lower back, the posture that caused it has usually been happening for hours already. That's the specific gap that posture-monitoring software is built to close: not willpower, but a second set of eyes that notices the drift while it's still small.
For the full research behind these numbers, with sources, see our evidence page. If you're looking for the practical fix rather than the background, here's our guide to fixing desk posture.