A variant is a specific version of a good — a t-shirt in Black / Medium, a sensor in the 24V option. Variants share the parent product but carry their own SKU and their own stock. You define variants by their option values (color, size, voltage), and stock is tracked per variant so you always know how many Black / Medium tees you have, not just how many tees.

A SKU (stock-keeping unit) is the code you use to reference a product or variant on orders, shipments, and stock counts. Each variant gets its own SKU so a warehouse pick is unambiguous. SKUs render in a monospaced font wherever they appear, since they are exact identifiers.

A product's unit of measure describes how it is counted — each, box, case, kilogram. Some goods are sold in one unit (a case of 12) but stocked in another (individual units); the conversion is handled when stock moves so your counts stay consistent regardless of how you sell.