A barcode is made of two things
The GTIN (Barcode number) and the symbology (Barcode), the type of barcode you need depends on what you need it to do
GS1 Specifications or requirements depend on the type and size of the barcode
For retail / point of sale (POS) products use a 13 digit GTIN encoded into an EAN-13 barcode.
For EAN-13 specifications click here
For very small retail products, you may need an EAN-8 barcode
For products that are not being scanned at POS and only scanned in the distribution centre / warehouse, such as shippers, cases etc a 14 digit GTIN is required
There are 2 symbologies that can be used to encode the 14 digit GTIN depending on if extra information such as expiry dates, batch numbers etc is required.
If extra information (expiry dates, batch numbers etc) IS required to be encoded, use a GS1-128 symbol
For GS1-128 specifications click here
If extra information is NOT required, use an ITF-14 symbol
For ITF-14 specifications click here
Version 1.0 14 Feb 2020