> For the complete documentation index, see [llms.txt](https://support.emarketeer.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.emarketeer.com/references/developer-advanced/barcodes.md). # Barcodes ## What is a barcode?
barcode scanner reading a barcode
A barcode scanner reading a barcode A barcode is essentially a font that computers can read visually. To read one, a computer needs a barcode reader — its "eyes." Like any font, you can encode whatever you want: numbers, text, full sentences. What you encode only matters if it means something to someone, or something, on the other end. For example, this phone number in a regular font: `004651410050` Your eyes read the digits and know what to do with them. The same number as a barcode looks like this:
phone number encoded as a Code 128 barcode
## Where are barcodes used? The most familiar place is your local store. The "beep" at checkout is a barcode reader scanning each product into the register. You also see barcodes on tickets, coupons, parcels, ID cards, and more. ## How can I use barcodes with eMarketeer? You need two systems: one to generate the codes and one to scan them. eMarketeer transports the code from one to the other. For example, you want to send coupons to your customers. You already have article numbers for the items and a cash register that scans barcodes. eMarketeer takes that information and sends a ready-to-print email with the offers and barcodes included. Customers print the email, bring it to the store, and the register scans the barcode to apply the discount. ## Barcode standards eMarketeer supports the following barcode standards. The default in eMarketeer blocks is **Code 128**. To change the standard, edit the barcode in Developer Mode. * Code 128 * Codabar * Code 11 * Code 39 * Code 39 Extended * Code 93 * EAN-8 * EAN-13 * ISBN-10 / ISBN-13 * Interleaved 2 of 5 * Standard 2 of 5 * MSI Plessey * UPC-A * UPC-E * UPC Extension 2 * UPC Extension 5 * PostNet --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://support.emarketeer.com/references/developer-advanced/barcodes.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.