Physical interaction.
WHAT DIFFERS
A finger is imprecise and obscures what it touches There is no hover state Screen space is limited One hand is frequently in use
WHAT THAT REQUIRES
Targets large enough to hit reliably Spacing so a near miss does not trigger something else No functionality depending on hover Primary actions within thumb reach
WHERE THE THUMB REACHES
The lower and middle portion of the screen.
WHAT THAT MEANS
Important controls low and central, not in top corners.
WHAT TO DO ABOUT HOVER-DEPENDENT FUNCTIONALITY
Provide an equivalent that works on touch.
WHY
Hover simply does not exist on most devices.
WHAT TO BE CAREFUL WITH
Fixed elements consuming screen space Elements appearing behind on-screen keyboards Horizontal scrolling introduced accidentally
WHAT CAUSES THAT LAST ONE
Usually one element with a fixed width exceeding the viewport.
WHAT TO PROVIDE
Feedback on touch, so a tap is confirmed.
WHAT TO TEST
Using the interface one-handed, on a real device.
