TLDR: Barcodes are those lines and patterns you see on products that can be scanned by machines. They represent data and are used to make things like supermarket checkout faster and more accurate.

A barcode is a way of representing data in a visual, machine-readable form. It consists of parallel lines of varying widths, spacings, and sizes. These lines, also known as one-dimensional (1D) barcodes, can be scanned by special optical scanners called barcode readers. Later, two-dimensional (2D) barcodes were developed, using different patterns like rectangles, dots, and hexagons. These 2D barcodes can be read by purpose-built scanners or by a digital camera connected to a computer running special software. Mobile devices like smartphones can also function as barcode readers using specific apps.

The barcode was invented in 1952 by Norman Joseph Woodland and Bernard Silver. It was based on Morse code and used thin and thick bars to represent data. However, it took over twenty years for barcodes to become commercially successful. They became widely used when they were adopted by supermarkets to automate checkout systems. The first successful system using barcodes was implemented by Sainsbury's, a UK supermarket, in 1972. Since then, barcodes have been used in many other industries and applications, such as healthcare, transportation, and document management.

Barcodes are read by barcode readers, which can be connected to a computer or built into mobile devices. These readers use light to scan the barcode and decode the information it represents. There are different types of barcode readers, including handheld scanners, fixed scanners, and smartphone apps. The data from the barcode is then used for various purposes, such as inventory management, product tracking, and identification.

Barcodes have become an essential part of our daily lives, making tasks like shopping and inventory management more efficient. They are used in supermarkets, libraries, hospitals, and many other places. Barcodes have also evolved over time, with the introduction of 2D barcodes like QR codes, which can store more information and are commonly used for marketing and mobile payments.

In summary, barcodes are a method of representing data in a visual, machine-readable form. They are used in various industries and applications to automate processes, improve accuracy, and enhance efficiency. Barcodes have become an integral part of our modern world, making tasks like shopping and inventory management faster and more convenient.