Product variant
A product variant is one specific sellable configuration of a product, such as a size, a colour, a capacity or a combination of them, each with its own price, its own availability and its own identifier.
Variants are where agent journeys break most reliably, because a variant is both a piece of data and a piece of interaction. The agent has to know the options exist, know which are in stock, and then actually select one. Any of the three can be missing on its own.
A page that shows swatches but describes no variants in its data leaves an agent unable to answer the shopper’s question. A page that describes variants perfectly but only lets you pick one by hovering leaves it unable to act on the answer.
Why it matters to a store
Check both halves. The data question is whether each option is described with its price and stock. The interaction question is whether an option can be chosen with a keyboard.