You are asking about QR codes,http://en.wikipedia.org/wiki/QR_code those little 2D bar codes with squares on three of the corners, erm right? It looks to me like the math is kinda hairy. I mean that Wikipedia article explains some of it, but if you want a full blown tutorial, this is the best one I have found so far:http://www.thonky.com/qr-code-tutorial/introduction/ So encoding and decoding these QR codes by yourself might be challenging. However, if you are looking for a handy online resource that can just sort of magically, and instantly, do the math for you, I recommend these: For decoding codes you already have in the form of a picture file, or a link to a picture file:http://zxing.org/w/decode.jspx For making new codes:http://zxing.appspot.com/generator Note that for the generator page there is a drop down menu at the top for choosing what kind of textual information you want to encode. Please note: for some kooky reason, the default on that QR generator is set to "contact information". Strangely this can look like the page is asking you for your contact information for some reason, but it really isn't. I mean you can just click the drop-down, and change it to "text" or "url" or whatever. Also I recommend not giving this page at appspot.com your real contact info under any circumstances, because I don't know who those people are, or what they might doing with such info.