Built into the camera on nearly every recent phone
QR recognition used to require a separate scanner app, but it is now built directly into the default camera on almost all recent Android phones, so scanning is often as simple as just pointing and tapping.
A quick safety habit worth building
Scanning an unfamiliar QR code is functionally the same as clicking an unfamiliar link -- most phones show a preview of the destination before opening it, and it is worth actually reading that preview instead of tapping through automatically.
Frequently Asked Questions
My camera will not recognize the QR code.
Some older models or camera apps have QR recognition turned off by default -- check your camera app's settings for a "Scan QR codes" option and make sure it is enabled.
How can I tell if a link from a QR code is safe?
Check the preview address shown on screen before tapping it, and be cautious with QR codes from an unclear source -- look closely at the address before opening it.