I2of5 Barcode (Interleaved 2 of 5 Barcode)
I2of5 (Interleaved 2 of 5) barcode is a higher-density version of Standard 2 of 5. It is used primarily in the distribution and warehouse industry.
Interleaved 2 of 5 barcode encodes any even number of numeric characters in the widths (either narrow or wide) of the bars and spaces of the barcode. Unlike Standard 2 of 5, which only encodes information in the width of the bars, Interleaved 2 of 5 encodes data in the width of both the bars and spaces. This allows Interleaved 2 of 5 to achieve a higher density.
The symbology is called "interleaved" because the first numeric data is encoded in the first 5 bars while the second numeric data is encoded in the first 5 spaces that separate the first 5 bars. Thus the first 5 bars and spaces actually encode two characters. This is also why the barcode can only encode an even number of data elements.