Why do bar codes have lines and numbers?

Barcodes consist of lines and numbers to encode information about a product in a machine-readable format. The parallel lines represent different widths and spacing, which correspond to specific data points, while the numbers typically provide a human-readable identifier, such as a product's UPC code. This combination allows scanners to quickly interpret the data, facilitating efficient inventory management and checkout processes. The use of both visual and numerical elements ensures accessibility for both machines and people.