When uploading a product, most merchants fill in name, price and image, then hit save. The remaining fields are not administrative detail — each has a direct effect.
GTIN and MPN
The global product number and manufacturer part number are what Google uses to match your product with the same product elsewhere and to show it in shopping results. Without them your product looks unidentified and loses free visibility.
Weight and dimensions
Carriers charge on volumetric weight, not just actual weight. A light product in a large box is billed on its volume. Leave the field empty and you hand cost estimation to a variable you do not control — usually not in your favour.
Quantity and low-stock alerts
Setting a low-stock threshold saves you the worst case: a customer buying something that is actually out of stock. Cancelling after payment costs you the customer and a negative review.
Brand and category
Correct categorisation is not only internal tidiness — it builds the category pages that bring you search traffic. An uncategorised product is one nobody reaches except by direct link.
A practical rule
Spend twenty minutes filling the fields properly at first upload. Re-editing a hundred products later costs many times that.