All products does not have to have GTIN (Global Trade Item Number). Especially, if it is one product like an artwork, it does not need to have a GTIN. However, if you sell more than one for each product, it will make your products unique in global market.
Why do I need to have GTIN?
Because it will definitely help you to be known in the global market. Customers can easily reach your products and it will help you to make your ads effective.
What is UPC?
UPC (Universal Product Code) is mostly used for the products from North America. It has 12 digit numbers. UPC is also known as GTIN-12 or UPC-A.