Most barcode symbologies require a calculated check character or checksum digit at the end. Some require two. These special characters allow the barcode scanner to verify that the barcode is not miss-scanned. It guarantees that the barcode is interpreted correctly every time.
But don't worry. Bars & Stripes takes care of all that for you. For all of the symbologies Bars & Stripes supports, check character calculations are performed according to specifications and the character is added at the end of your barcode automatically.
But if you're curious to see how we calculate the various check characters, we've provided these handy calculators.