A SKU (Stock Keeping Unit) is a unique identifier a merchant assigns to a specific product variant so it can be tracked, counted, and ordered without ambiguity. Unlike a barcode or manufacturer part number, a SKU is internal to your business and follows your own naming logic. In Shopify, every variant can carry its own SKU, which is what ties a line item on a quote back to the exact item in your catalog.
How it works
A SKU is usually a short alphanumeric string that encodes attributes you care about, such as product type, size, color, or location. For example, a blue cotton t-shirt in medium might be TSH-BLU-M. Shopify stores the SKU at the variant level, so a single product with several sizes and colors will have a distinct SKU for each combination. Inventory counts, reports, and fulfillment all key off that value.
Why it matters in B2B quoting
Wholesale and B2B orders often run to dozens of line items, and buyers frequently reference products by SKU rather than title. Including SKUs on a quote removes guesswork: the buyer confirms they are ordering exactly what they expect, and your team pulls the right stock when the quote converts to an order. Because Shopify draft orders and quotes reference the same variant records, a SKU carried on a quote line stays consistent through to checkout, invoicing, and fulfillment. See the B2B quoting glossary for related terms like purchase order and draft order.
Example
A distributor requests 200 units across four variants. Each requested line shows its SKU (WGT-500-BLK, WGT-500-SIL, and so on), quantity, and price. When the quote is accepted, those SKUs map directly to the inventory that ships, so nothing is mismatched between what was quoted and what is picked.
Good SKU practices
Keep SKUs short, consistent, and human readable. Avoid spaces and special characters, never reuse a retired SKU for a new product, and decide on a format before you scale your catalog.