Basic Bar Code Structure

Most barcodes are "license plates" that identify an item. When read, can be used to look up additional information about the item. Data is read from barcode, sent to a computer, and the computer looks up the price and description of the item from the computer's database.

Read by:

• scanning a spot of laser light across
• the entire barcode
• taking a digital picture of the barcode
• with a CCD digital camera

Relative widths of both the bars and spaces - code the data stored in the barcode. Reader detects these relative widths and decodes the data. There are about 400 different types of barcodes.

A typical barcode consists of the following:

• Quiet Zone – a large space with no printing (sometimes called the “Clear Area”)
• Start Code – Indicates the start of the barcode
• Data – The actual data the barcode stores (Check Digit) –A mathematical sum that is used
  to verify the accuracy of the other elements of the barcode, (not always present)
• Stop Code – Indicates the stopping point of the barcode
• Trailing Quiet Zone – Another clear space with no printing

Density or Resolution

• High Resolution (less than 0.23mm)
• Medium Resolution (0.23mm to 0.50mm)
• Low Resolution (greater than 0.50 mm)
• Rule: For effective scanning with any device, use lowest barcode density possible that will print on a given area on label or page.
• Code 39 and Code 128 are best choices for most barcode solutions
  

Basic Structure
Symbologies
Components
Benefits
Bar Code Solutions
Bar Code - History