¹ Share links using a camera enabled smart phone with optional barcode scanner.

(Barcode definitions from Wikipedia)

QR Code (1^st): A QR code is a specific matrix barcode (or two-dimensional code), readable by dedicated QR barcode readers and camera phones. The code consists of black modules arranged in a square pattern on a white background. The information encoded can be text, URL or other data. Common in Japan, where it was created by Toyota subsidiary Denso-Wave in 1994, the QR code is one of the most popular types of two-dimensional barcodes. QR is the abbreviation for Quick Response, as the creator intended the code to allow its contents to be decoded at high speed.

DM Code (2^nd): A Data Matrix code is a two-dimensional matrix barcode consisting of black and white "cells" or modules arranged in either a square or rectangular pattern. The information to be encoded can be text or raw data. Usual data size is from a few bytes up to 2 kilobytes. The length of the encoded data depends on the symbol dimension used. Error correction codes are added to increase symbol strength: even if they are partially damaged, they can still be read. A Data Matrix symbol can store up to 2,335 alphanumeric characters. Data Matrix symbols are rectangular in shape and usually square, they are made of cells: little elements that represent bits. Depending on the situation a "light" module is a 0 and a "dark" module is a 1, or vice versa. Every Data Matrix is composed of two solid adjacent borders in an "L" shape (called the "finder pattern") and two other borders consisting of alternating dark and light "cells" or modules (called the "timing pattern"). Within these borders are rows and columns of cells encoding information. The finder pattern is used to locate and orient the symbol while the timing pattern provides a count of the number of rows and columns in the symbol. As more data is encoded in the symbol, the number of cells (rows and columns) increases. Symbol sizes vary from 8×8 to 144×144.

HCCB Code (3^rd & 4^th): High Capacity Color Barcode (HCCB) is the name coined by Microsoft for its technology of encoding data in a 2D "barcode" using clusters of colored triangles instead of the square pixels traditionally associated with 2D barcodes.[1] Data density is increased by using a palette of 4 or 8 colors for the triangles, although HCCB also permits the use of black and white when necessary. It has been licensed by the ISAN International Agency for use in its International Standard Audiovisual Number standard,[2] and serves as the basis for the Microsoft Tag mobile tagging application .