Hey there, @EJC !
Ryder here, from the Social Care Team at Shopify. Thanks for posting! Are you looking to add a Stock Keeping Unit (SKU) or a Barcode number to your products?
For both of these fields, you can enter unique numbers to each individual product variant - regardless of size or colour. You can include this data in the CSV file that you upload, or update your existing products in the Bulk Editor by selecting the “Add fields” drop-down and choosing SKU or Barcode. Each product variant will have it’s own field to input unique numbers:
If you’re looking to create scannable barcodes for your products to sell in-store, you can look at installing the Retail Barcodes app and follow this guide to help you setup and create a barcode template. Are you using our POS app to sell in person? If your business is located in United States, Canada, United Kingdom or Ireland you can purchase hardware for your retail store - like Barcode Scanners or Barcode Printers.
I hope this information helps! If there’s anything I can clarify, please let me know and I’d be happy to see how I might be of assistance.
Cheers.