SKU

Every sellable unit, meaning every variant in size, color or configuration, needs a unique SKU. It identifies the item across systems: Shopify, ERP, warehouse management, fulfillment providers and marketplaces all reconcile inventory and orders via the SKU. Without clean SKUs there is no reliable stock synchronization and no trustworthy product analytics.

Good SKU schemes are descriptive but stable: they encode, say, category, model, color and size (e.g. TS-CREW-BLK-M) and never change once assigned. The SKU is your internal article number, not to be confused with the GTIN/EAN, the manufacturer's global, standardized barcode.

In migrations and integrations, the SKU is the most important mapping field: old and new systems are linked through it. Changing SKUs mid-migration is one of the most common causes of inventory chaos and should be strictly avoided, or versioned cleanly if unavoidable.