A supplier is a business partner who provides the customer with materials or services. A supplier can be found in almost every trade or production, which is why they are indispensable in (multi-stage) supply chains. He can be both a manufacturer or a trader of a good/service. In addition, a distinction is made between the individual supplier levels, starting with the upstream supplier, who supplies raw materials and supplies. This is followed by the supplier from the wholesale trade responsible for delivery to the retail trade. Known from a typical automotive supply chain, there is also the supplier who manufactures parts for production, but does not sell any end products himself. The added value of these processes turns a supply chain into a value chain.