What is the Fn Lock icon used for and how do you turn it off and on?

One key to rule them all.

By Robin Bea Nov. 15, 2026 2:15 pm EST Todudom/Getty Images Add Engadget on Google: Google Discover

Not every keyboard has one, but if yours has a key marked Fn, F Lock or Fn Lock, it might not immediately be clear what it does. Pressing one of these keys alone does nothing. At most, depending on your configuration, it might turn the Fn Lock key indicator on. Even more confusingly, you may have an Fn key and see Fn Lock or a lock icon printed on a different key with no indication of what either does.