What does SKU on the add item page mean?

[Guest lord]

Having SKU numbers on items is fantastic!

[Sofie-Sham Miller]

SKU (Stock Keeping Unit) is a unique code given to each of your items. Specify and fill in each field individually. We recommend using numbers of the format "10001", "10002"... etc. but the main thing is that no numbers are repeated. One last condition is that the SKU should not exceed 40 characters.