This document discusses how libraries can use QR codes. It begins by explaining what QR codes are and how they work, storing large amounts of information in a barcode that can be scanned by smartphone cameras. It then provides many examples of how libraries are using QR codes, such as linking to audio books, research guides, maps and contact information. It encourages librarians to consider QR codes for instruction, events and promotions. While noting they may not be suitable for all users or purposes presently, the document advocates experimenting with QR codes and pedagogical uses.