In today's world we live in a highly developed, consumer-oriented society. Much depends on the exchange of goods and services. In this environment, consumers need to get acquainted with them to encourage the exchange of goods. One useful, and now an indispensable element in this process, are also social networks. They are used all over the world by several billion people, and this has been well recognized by the companies, which have begun to use them for advertising, informing and communicating. It has become easier for people to look for information about products and services on the Internet, rather than physically going to a sales outlet. In addition to the above, some of the most popular social networks have been analyzed in this paper, as well as an explanation of how they function, and also the possibility of advertising on these networks. Since the act of buying itself involves complex psychological processes in the background, this subject was also addressed. Larger food companies has been used as an example, and their social networking advertising was analyzed, which is complementary to the research in this paper, because we will be able to conclude that their activities have been memorized by potential buyers and how they perceived the marketing campaign of these companies. The key research thesis have been confirmed in the research - marketing product management affects the buying decision, and good marketing campaigns will have a positive impact on the buying decision, while a bad marketing campaign will produce counter effects and deter people from purchasing.