The Barcode reader is used by checkout scanners and inventory trackers. The parallel lines are the scannable part of the UPC or universal product code. The reader is an optical scanner that decodes the data and sends it to a computer. Inside the reader, you will find a lens, a light source, and a light sensor. The sensor steadily translates the optical indicators into electrical actions.
Readers can have two types of construction. They can be one-dimensional or two-dimensional. One-dimensional readers translate vertical lines only into data while 2-D readers can translate geometric patterns like rectangles, dots, and hexagons.
Do not confuse the barcode with the QR code. They are unique and very different. The barcode is found everywhere, where the QR code is unique to several industries: automobiles for which it was originally designed, and marketing and advertising campaigns. QR stands for quick response. While it is a code, it is not a barcode.