The same finger press produces three different characters depending on which side of a border your operating system thinks you're on. Travellers, remote workers and anyone with a foreign laptop meet this weekly — here is the map.
US QWERTY: the baseline
Shift + 2 → , Shift + ' → ", Z is where Z should be. If your keyboard disagrees with this paragraph, you're not on US — keep reading.
UK QWERTY: the swap
@ and " trade places, £ gets Shift + 3 instead of #, and Enter is tall. Windows installs both US and UK from one English download and flips between them on Win + Space — the full removal walkthrough is in wrong keyboard layout. Mac users: UK puts @ on Option + '.
German QWERTZ and French AZERTY
German swaps Z/Y (hence QWERTZ), hides @ on AltGr + Q, and gives ä ö ü their own keys plus its own (see eszett). French AZERTY moves A/Q/W/M around, needs Shift for digits, and types é è ç from dedicated keys. Borrowed laptop? Check the taskbar indicator before assuming anything is broken.
The rule
Hardware is innocent until proven guilty: identify the layout first, switch with the shortcut, delete what you don't own. Accents themselves are covered per-letter — start with ñ or browse all accented letters.