who is eligible ?
You can be a visitor from Non EU further not decided to come in immediate future.
European citizens permanently living in non EU countries.
You talk to the shop assistant in some cases; the shop itself will refund you.
In other cases, the shop will use a third party to organize the refunds on its behalf.
Even in many cases
You will receive an invoice for the goods. You must show the invoice, the refund form, the goods and any other necessary documents to the customs officers of the last EU country you leave. The customs officers must stamp the form as proof of export. Without the stamp, you will not obtain the refund