A purchase order is a buyer's request to a seller to order goods.  

A purchase order is not an active order upon creation but upon acceptance from the seller. Generally, the item(s), prices and quantities have already been negotiated. Once accepted by the seller, a purchase order becomes a legal agreement to provide the mentioned goods at the agreed-upon price.

A Purchase order must includes

1. Company information (name etc.)

2. Shipping details (address)

3. Vendor information (name and address)

4. Order information (product, price, and quantity)