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.
The Fn and Fn Lock keys are most often found on laptops, but they appear on some standalone keyboards as well, especially smaller ones, like Logitech's G512 X. They're used with the function keys (the F1 to F12 keys on the top row) to add support for more controls to compact keyboards or, in the case of Mac users, activate Google's Gemini AI. Their exact functions and how you turn them on and off vary depending on your keyboard but there are a few basic ways they work.
You can think of the Fn key similarly to the Shift key. When you want to activate it, you need to keep it held down the whole time you're using it. While it's held, it will switch between the function keys'
