
My clients still ask about the function keys on computer keyboards, so I have updated a blog post from 2010
Which keys are the function keys?
The function keys are marked F1 to F10 (or F1 to F12) on the top row of the keyboard. Typically, each of these keys performs two different functions:
- The task assigned to the number of the key (eg F5 may be assigned the “find” command)
- The task indicated by an icon on the key itself

How does the key know which of these two functions to perform?
- Pressing the key on its own causes the action indicated by the icon (eg turn the sound off)
- If the key marked “Fn” is depressed and then (with the Fn key still depressed) the function key is pressed, then the action assigned by the program you are using will be carried out. The “Fn” key is usually to be found at the lefthand side of the bottom row of the keyboard

So, what actually happens when you press “Fn” together with a function key
It depends on how the program you are using has set them up. In Word, for instance, pressing the F5 key executes a “find and replace” command in the same way as clicking the “replace” instruction on the ribbon of commands at the top of the screen.
The whole point of the function keys is that they perform different functions depending upon the program that is using them. Over time, though, some of them have become more-or-less standardised. For instance, the F1 key almost always invokes the “Help” system for the current program.
You need to experiment a bit to find out how a particular program uses the function keys (or you could try pressing F1 to see if it lists the function keys and their uses in that program).
What do the symbols on the function keys mean?
Sorry about this, but, once again, it depends. This time it depends on the particular keyboard. The best way to find out is probably to experiment, but do not have any programs such as Word loaded when you do this as you may get unexpected results and you wouldn’t want to harm a document.
Some of the common icons and their uses are:
- A moon – puts the machine into sleep mode
- Two different versions of suns – increase and decrease the screen brightness
- Loudspeaker – turn the sound on
- Loudspeaker crossed out – turn the sound off
- Various icons that denote increasing and decreasing the volume (eg loudspeakers with “waves” coming out of them)
- Computer screen(s) – switch the output to/from an external monitor

Will I break anything if I play with these keys?
No. The worst that may happen is that you get confused about what you have changed. Re-starting the computer will take you back to where you started as far as the function keys are concerned.
Are function keys important?
Not really. If this is a bit confusing then there is no need to worry about using them at all. There is always an alternative to using them.
Also, some of the actions that used to be assigned to function keys (eg checking the battery level, turning wifi on and off) are now handled by Windows.
What’s more, in writing this update I’ve discovered that most of the function keys actually no longer have any use at all in Word. Nothing happens when you press them. I haven’t checked whether this is the case in other programs.
Are function keys being phased out? Maybe.
Microsoft looks at keyboards generally
Minitool offers a more comprehensive look at function keys
Apple details the function keys on a Mac
Here’s another blog post of mine looking at keyboards – More Key Explanations