You can embed all types of information into QR codes. Specifically, URLs, email addresses, phone numbers, SMS services, and general text are great uses for QR codes.
Things to Remember When Creating QR Codes:
Most modern smartphones will read QR Codes without a special app. Just point the phone's camera at the code, and the software will ask if you want to open the link in a browser. If you prefer to use a separate app, here are some recommendations: