5. Scoops are just better than bars.
What are Scoops/Bars? Those aren't mentioned in the glossary.
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They are differences on the F and J keys to help touch-typists find the home keys.
Bars are short raised sections along the lower edge of the keycap.
Scoops are where the keycaps are dished slightly more than the other keys.
There are also nubs - small raised pimples usually in the centre of the keycap, although you're more likely to find those on the 5 key on a numeric keypad.
Bars are, of course, the best option out of these