The main theme of this paper is cosumer behavior and a key factors affecting their behavior and the final decision to purchase a particular product or service. Consumer behavior is a complex process influenced by a number of external and internal factors. Each consumer chooses products that are in accordance with his / her wishes and expectations, and marketing experts must continually monitor the needs of consumers to achieve maximum customer satisfaction and achieve market competitiveness. Based on the analysis of external and internal factors, it is evident that each factor is unique to each customer, in other words, there are no two people who behave and react when it comes to a product or service. The objectives of the work identified how and in which way consumer behavior is influenced by personal, psychological and social factors. Some of them are very complex and have a strong impact, so today, with a more diverse offer and numerous marketing methods, customers are trying to point to the purchase of a particular product.