on the paperwhite you have to tap or swipe the screen to turn the page. My very old kindle had a button, but the best of all was my medium old kindle which had a kind of capacitive page turn that sensed you were pressing harder with your finger. Difficult to describe, but probably some physicist could!
Its a pain because i have a hand disability (among other disabilities) and with the medium odl one i could do it all with one hand, whereas the new one is a bit heavier and i dont have the dexterity to do it with one hand