ไขข้อสงสัยว่าทำไมต้องมีขีดเล็กๆนูนๆใต้ ปุ่ม F และ J

Answer:
The bumps or ridges found on the F and J keys on the keyboard helps users correctly position their left and right hand on the keyboard without having to look at it. For example, without looking at the keyboard you can easily position your left index finger on the F and the right index finger on the J, which then positions all the remainder of your fingers in the correct position. People who touch-type (type without looking) use these two ridges to determine the position of their fingers on the keyboard.