These bumps show you where your "Home Keys" are by touch.
If you type in the correct way, your pointer fingers should rest over the "F" and the "J". These bumps allow you to find these keys by touch so you do not have to glance down at the keyboard to know where your fingers are.
There are many products to enhance or act as visual aids.
Example. www.keyboardbumps.com
Because it shows the home row keys.
The bumps on the f and j keys are to find home row (aka. "asdf jkl;") without looking at the keyboard
touch typing using the bumps on the F and J keys to tell where to put your index fingers.
The F and J keys usually have some sort of physical indicator (e.g. raised letters, bump on the key, etc.). This is to aid touch-typists who place their left index finger on the F key and their right index finger on the J key to indicate the "home row."
so you can find the five key without looking. It`s similar to the bumps on the f and j keys on a keyboard.
J.-F Reymond has written: 'J.-F. Reymond' -- subject(s): Exhibitions
J. F. A. Soza was born in 1919.
F. J. Rowe died in 1909.
F. J. Rowe was born in 1844.
F. J. McCormick died in 1947.
F. J. McCormick was born in 1889.
J. F. A. McManus died in 1980.