Why are there two sets of the Ctrl, Alt, and Shift modifier keys when only one of each is necessary?

  • 10
    Do you only have one hand? – random Jun 30 '11 at 4:24
  • 1
    As a member of the sinistral minority, I appreciate not having to use my right hand for everything. – pavium Jun 30 '11 at 5:19
  • The two ALT keys are actually different, with the ALTGr key usually the same as pressing CTRL+ALT. – paradroid Jun 30 '11 at 8:38
  • Several questions are marked as duplicate of this question. This should be re-opened or the others marked as closed for a better reason. – RJFalconer Oct 24 '16 at 14:29

When touch-typing, you use the alternate side "function" keys.


qwer,asdf,zxcv you'd use the right shift with your right hand without needing to stretch your left hand while pressing one of the aforementioned keys.

  • Ergonomics FTW. – surfasb Jun 30 '11 at 4:32
  • The 1, 2, 3, 4, 5, T, G, and B keys (plus a few others) are missing from that list -- these should also be used in conjunction with modifier keys on the right-hand side of the keyboard. – Randolf Richardson Jun 30 '11 at 5:35
  • 2
    I figured Prasanth knew what I meant. I'll be sure to define myself more thoroughly next time. – Zac Bruce Jun 30 '11 at 6:11

These modifier keys are very important for professional typists. If there was only one modifier key for CTRL, Alt, and Shift, then typing speed could be slowed down when one of these modifier keys was needed.

There is a concept of a "dividing line" which is supposed to be like this (and can be seen in the coloured keyboard image included below which comes from an instructional typing program which was probably designed for children):

  • For the Right-Shift key all the keys on the left up to: 5, T, G, and B

  • For the Left-Shift key all the keys on the right starting from: 6, Y, H, and N

(The same usage applies for the CTRL and Alt modifier keys.)

Unfortunately function keys are a bit of a mess depending on how the keyboard manufacturer designed the spacing, but traditionally they're grouped in three groups of 4 keys with F1, F2, F3 and F4 on the left-hand side, and F5 through F12 on the right-hand side, of the dividing line.

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