A menu displayed outside Palace Cafe has a QR code for customers to pull up menus on their phone, a new tactic to reduce contact as restaurants reopen. Staff photo by Ian McNulty ...

Now, when you walk in to many restaurants you'll find a QR code on tables or at the front door. Just by putting your phone’s camera over that code, the restaurants menu pops up.

The QR-code menu—which you access by scanning a black-and-white square with your smartphone—has taken off ever since. It may dominate going forward.