The Reason why bumps are on the F and J keyboard keys?

The small bumps or ridges found on the F and J keys on a computer keyboard are to help users correctly position their left and right hands without having to look at the keyboard. For example, without looking at your hands, you can feel the correct position of your left index finger on the F and the right index finger on the J by feeling the small bumps on the keys.
Once you're hands are on the home row key position, you should be able to locate the remainder of the keys on the keyboard.