How do you actually read dog body language?
By reading the whole animal in context rather than any single signal — because almost every individual signal is ambiguous, and the most commonly misread dogs are the ones people describe as biting "without warning", which almost never happens.
The escalation sequence, which is what matters most. Dogs communicate discomfort through a graded series, and the early signals are subtle:
Looking away, turning the head, and blinking.
Lip licking when no food is present, and yawning when not tired. These are the two most commonly missed stress signals, and they appear constantly in photographs of children hugging dogs.
"Whale eye" — the whites of the eyes showing as the dog holds its head still and moves its eyes.
Freezing, which is a serious signal and frequently read as the dog being calm or tolerating something. Stillness is not consent.
Moving away, which should always be allowed.
Growling, which is information, not a problem — a dog that growls is warning rather than biting, and punishing it removes the warning.
Snapping without contact.
Biting.
So "no warning" almost always means the warnings were given earlier and not recognised, which is the most important thing an owner can learn.
Signals that are ambiguous rather than meaningful alone:
Tail wagging, where speed, height and direction change the meaning entirely — a high, stiff, fast wag is arousal, not friendliness.
A "smile", which may be a stress grimace.
Rolling over, which can be an invitation or appeasement — and approaching to rub the belly of an appeasing dog is a common bite scenario.
Barking, which serves many functions.
Play bows, which are clearer and indicate genuine play.
What to read instead: the whole body — weight forward or back, muscle tension, ear position relative to that dog's normal, mouth tension, and whether movement is loose or stiff.
Context, always. The same posture means different things near food, on a lead, in pain or cornered.
For children: teach them to let the dog approach, never to hug, and never to disturb a sleeping or eating dog — and supervise genuinely rather than nominally.
General information, not behavioural advice.