The bumps on the F and J letters on the keyboards assist users in locating the exact keys without having to glance at the keyboard. The sole reason there are bumps on these two keys is because they represent the correct hand position for typing. The left hand covers A, S, D, and F, while the right hand covers J, K, L, and the semicolon by placing the two index fingers on these two keys.
Thumbs are pressed against the Space button. June E. Botich invented the keyboard bumps as a technique to improve the speed and precision of keyboard users.