When I was a child I stumbled upon a simple diagram that explained some of the elements found in a basic supermarket barcode. I was fascinated by its complexity and at the same time I couldn't believe how easy it was to understand. I remember feeling like I had found the ultimate decoder ring.

Number System Character - This digit identifies the type of manufacturer or how the barcode will be used. For example 0, 6, and 7 are generally used in the retail industry, while 3 is assigned to the health and drug manufacturing industries.

Number System Bars - These bars correspond to the Number System Character.

Manufacturer ID Number - Each company must apply for a Universal Product Identification Number with the Uniform Code Council. The UCC assigns each company a unique six digit identification number for use on all of their products. The number is composed of the Number System Character and a five digit manufacturer's code.

Manufacturer ID Bars - These bars correspond to the Manufacturer's ID Number.

Tall Center Bar - These bars serve as a middle reference point for the scanning devices.

Item Number - Each company is responsible for assigning a unique five digit number to each of their products.

Item Bars - These bars correspond to the Item Number.

Modulo Check Character - This digit is derived from a mathematical formula based on the unique set of numbers in each barcode that helps ensure the accuracy of the data scan.

Modulo Check Bars - These bars correspond to the Modulo Check Character.

Right Hand Guard Bars - These bars serve as an ending reference point for the scanning devices.

Uniform Product Code version A is a widely used style of barcode in retail stores for sales checkout.

Version E is a compressed UPC A also called Zero Suppressed. Used on small items like cans of soda, cigarettes, and candy.

European Article Numbering encodes 13 characters and is used throughout the world (except for USA and Canada) to mark physical goods in retail shops.

International Standard Book Number includes the price of the book in the barcode. The last 5 digits in this example translate to $44.95 US dollars.

Barcode used by the United States Postal Service to automatically sort mail. The code is made with evenly spaced bars of two different heights.

Code 3 of 9 is a variable length symbol commonly used in military and health applications. I got this example from my college ID card.

Full alpha-numeric barcode that supports both upper and lower case characters.

Two-dimensional barcode which can store 2,000 ASCII characters. It can encode a lot of information in a small space.

2D symbology used by UPS to sort and track packages. This barcode can be read at extremely high speeds.