Not every laptop uses this keystroke, but most seem to.
If you’re on a plane or in a hospital, you should disable your wireless receiver. Or suppose you’re riding in a train or car and you know there’s no wireless signal, you’ll increase your battery performance if you disable the wireless receiver.
Hit Fn+F2 and it’ll toggle wireless on and off. (Practice it a few times so you can recognize how the icons in the system tray appear, so you’ll know to switch it back on if you ever disable it by accident.)