Barcodes are codes represented by lines that identify products through a barcode scanner connected to a computer system. Barcodes use varying widths of black and white lines or spaces to represent numbers and letters. There are different types of barcodes like linear barcodes, which use combinations of narrow and wide bars, and 2D barcodes, which can represent more data in a given area. Barcodes are read by scanning the lines with light and measuring the white spaces and black bars to decode and process the data they represent. They provide benefits like increased speed and accuracy of data entry over manual systems. However, barcodes can be damaged or not scan if the label is on an oddly shaped product.