QR codes can store different types of data like numbers, letters, and Kanji characters. They were invented in 1994 to label automobile parts and consist of black squares arranged in a grid on a white background. QR codes can contain URLs, images, PDFs, maps and other data readable by smartphone cameras. The document discusses using QR codes in medical prescriptions and airports to provide medication instructions and prevent wasted flight tickets. QR codes offer benefits like universal accessibility, reduced medication time, and increased customer engagement.