QR codes (Quick Response Codes) are similar to traditional barcodes.  However, instead of representing a number, the pattern of dark squares represents encoded text, usually a message, website or contact information.

 How do I use it?

You must have a phone or other smart device with a camera.  Some phones have a QR code reader already installed, otherwise you need to download a QR code reader.  Most are free downloads.  Once you have a QR code reader on your phone, simply point the camera at the code. Some readers automatically read the QR code while others require you to “take a picture” of the QR code.  Some QR code readers work better on certain devices, so read reviews and try a few until you find one that works for you.

 What does it do?

You can scan the QR code and receive different types of information depending on what is encoded and the capabilities of your QR code reader.

In the library catalog, the QR code will provide the location, call number and availability of a book.   

The library is exploring other uses of QR codes.  For example, the code on a poster or exhibit might take you to a website, or open an email application with the “To” field filled in.  

Is there any risk?

Most QR codes are safe to use.  But malicious QR codes can contain viruses, so be cautious of QR codes that show up in unsolicited emails or that you find on suspicious websites. 

 Wikipedia article