A set of actions aiming to fulfill a defined goal. The entire purchase process consists of particular stages, such as defining needs, market analysis, choice of supplier, purchase realisation and purchase assessment. The first stage is necessary to start a purchase transaction and define a purchase need. The latter can be modified or expanded according to customer’s needs. At the realisation stage it is necessary to define in details the cooperation conditions, so that the customer is happy with the purchase, and assesses the process in a positive way.