How to tell on your own hair
Wash, condition, skip all styling products and let your hair dry untouched. Strands that bend into an S but don’t wrap all the way round are waves; strands that wrap into a loop you could fit a finger or marker through are curls. Long or heavy hair can pull curls into waves near the roots, so look at the ends as well.
When you have both
Wavy on top and curly underneath is common. Style the whole head for the curlier parts, with a lighter hand on top: less leave-in where waves fall flat, a little more where curls form.
What changes on wash day
Waves: shampoo the scalp, condition the ends, skip or go light on leave-in, foam or gel on wet hair (soaking wet or damp, as its label says), no brushing once dry. Curls: condition generously and detangle with it in, leave-in plus gel, refresh between washes.
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