What is Inventory?
Also known as: Stock
Inventory is the quantity of each product you currently have available to sell, tracked so that stock levels on your store reflect physical reality.
Accurate inventory prevents overselling — accepting an order for something you cannot ship, which damages trust more than almost any other operational error because the customer has already paid.
Decrement stock when the order is placed rather than at dispatch, and reconcile recorded against physical stock on a regular schedule. Weekly is sufficient for most small sellers.