Proforma invoice is basically a purchase order
Performa invoice is basically a purchase order and it’s a confirmed one by nature. When a business signs performa invoice with a purchaser then that means they are surely going to transact. Performa invoice is signed before products or goods are shipped to the buyer.
Performa invoice gives the seller a surety that the buyer pays for the products. It is mostly used in international transactions or in transactions where the seller has to ship products to a distant place to the buyer.