A printed technology using “black and white” bars to encode the data. From early beginnings of simple barcodes that could only encode a few digits, today there have been over 250 barcodes invented. Luckily many of them have fallen by the wayside and we only concentrate on a few of these. Linear barcodes including U.P.C./EAN that we see every day on all our retail purchases are perhaps the most pervasive, however, the new two-dimensional barcodes that include error correction and detection are becoming more used. Large amounts of data can be stored on a small symbol, making them very useful for marking small objects. The cost of printing a barcode is very low, but they cannot be changed without replacing the label. Common linear barcodes include: U.P.C./EAN, Code 128, Interleaved 2 of 5, and Code 39. Common 2D codes include PDF417, MaxiCode, and Data Matrix.