Barcode 101 Continued...Elements of a Barcode
These are the wide and narrow black bars and whites spaces contained in the bar code.
In some bar codes, like Code 39 (same as Code 3 of 9), each character is printed independently of other characters. These characters are not meant to be read as one coherent line and are therefore separated by what's called an inter-character gap.
When exaggerated, you can see the elements for each character and the inter-gap that separates the characters.