A listing is a seller's offer on your marketplace: a title, a description, a price, and a status — Draft while it is being prepared, Active while it is on sale, Paused when it is temporarily withdrawn, and Archived when it is finished for good.
One limit must be stated plainly, because everything downstream respects it: a listing is words and a price — it is not linked to your product catalogue. It holds no stock, promises no availability, and knows nothing of warehouses. That is deliberate. The goods in a marketplace sale are the seller's affair and live in the seller's own records; your module records the commercial facts — what was offered, what it sold for, what you kept and what you owe. When an order is recorded (§13.5, Orders), a line can name the listing it came from — which fills in its title and price — or stand as free text; either way, no stock moves and none is promised.