Traditional barcodes, such as those printed on product packaging, are also known as one dimensional barcodes. There are several types commonly used, including UPC and EAN. Most look similar to this:
These 1D barcodes contain a unique code which typically describes a product, like a CD or a book. You can look this code up on the internet to find reviews, additional information and more.
If you scan a book, you can also search for the book in an online book shop.