A symbology is a kind of barcode: the rules for turning a value into bars or dots. Labeljoy makes 66, counting the versions some of them come in - EAN 8 and EAN 13, the seven kinds of Databar, Micro QR and more. You choose one with Symbology, in the Barcode section, where they're grouped as on this page; each has a page of its own, with what it holds and what can go wrong.

Choosing one. Often the choice is made for you: a product sold in shops needs the EAN or UPC number GS1 gave it, a carton an ITF 14 or a GS1-128 (Code 128 with GS1 data), a book its ISBN, a letter the postal service's own barcode. For codes of your own, Code 128 suits a short value read by any scanner, and a QR Code or Data Matrix holds much more in a small square - and a phone can read a QR Code.

The symbologies
Linear	Channel Code, Codabar, Code 11, Code 128, Code 2 of 5, Code 39, Code 93, EAN, Flattermarken, ISBN, ITF 14, MSI Plessey, Telepen, UK Plessey, UPC
2D	Aztec, Code One, Data Matrix, Dot Code, Grid Matrix, Han Xin Code, Maxicode, QR Code, Ultracode
Postal	Australia Post, DAFT Code, Deutsche Post, Dutch Post, Facing Identification Mark, Japanese Postal, Korean Postal, Planet Code, PostNet Code, Royal Mail, USPS Intelligent Mail
Stacked	Codablock F, Code 16K, Code 49, Databar, PDF 417
Pharmaceutical	Code 32, Pharmacode, Pharmazentral Nummer

Some symbologies come in more than one version - EAN 8 and EAN 13, the kinds of Databar - which you choose with Mode. They're on the symbology's page. GS1-128 and GS1 DataMatrix aren't in the list: they're Code 128 and Data Matrix with GS1 data, see GS1 and HIBC data.

The ones you use most can go to the top of the list: click the pin next to a symbology to add it to Favorites.