A two-dimensional barcode used for mobile tagging. Microsoft Tag is a four-color variation of Microsoft's "High-Capacity Color Barcode" (HCCB), which uses eight colored triangles to provide a capacity of approximately 3,500 alphabetic characters per square inch. The barcodes can also be read in low light and even when the image is blurred. Like other mobile tagging systems, apps are available for popular smartphones.Triangles and CirclesThe basic tag is composed of color triangles, but a custom tag using color dots allows a logo to occupy the entire background (see below). See barcode and mobile tagging.