Data Capture

Bar Code Basics

Bar codes use a system of bars and spaces to encode data, based on a language known as a symbology. A bar code mark is applied to items so that information about those items can be collected using automated techniques. Bar code symbologies are either one dimensional (1D or “linear”) or two dimensional (2D), based upon how the code is designed to be read.

1D Bar Codes

Many industries standardize on certain symbologies for their applications. One of the best known 1D symbologies is the UPC (Universal Product Code), which is common in grocery and retail applications. Code 39, which was developed by Intermec in 1974, is still one of the most widely used alphanumeric bar code symbologies in the world.

2D Bar Codes

Because they encode data in two dimensions, 2D bar codes can hold more data in a smaller space than can a 1D bar code. In a world where more data is always needed, 2D’s greater data capacity has contributed to its growing popularity across a variety of applications.

There are two main categories of 2D bar code symbologies: stacked and matrix.

2D Stacked

2D stacked symbologies are made up of two or more rows of linear bars and spaces. Leading stacked symbologies include PDF417, Code 16K, Code 49 and a version of GS1 DataBar formerly known as RSS Composite.

2D stacked symbologies can be read by laser scanners, linear imagers and area imagers, although not all readers can process all symbol sizes.

2D Matrix

2D matrix symbologies encode data in dark and light geometric elements arranged in a grid. The position of each element relative to the center of the symbol is a key variable for encoding. Matrix symbologies are commonly used for small item marking, and also for unattended and high-speed reading applications. Examples include Data Matrix, MaxiCode, Aztec Code, Code One and QR Code.

2D Matrix symbologies can only be read by area imagers.

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