The growth of the Internet heavily influences people's lives every day, especially by the development of Social Networking Sites (sns), which since their first appearance have been constantly recording a growing number of users. The main purpose of this paper is to identify the significance of sns in relation to two activities of individual users: communication and consumer behaviour. The study focuses on the three most popular sns in three neighbouring countries (Germany, Poland, and Russia) namely, Facebook, vkontakte, and YouTube. The methodological approach is twofold: firstly, the authors developed a theoretical background of the areas of using sns and formulated research questions; secondly, they applied the papi and cawi methods for the data analysis. Regarding the researched activities, it should be noted that sns users use these platforms more often for communication than consumer actions. The most useful here is Facebook in comparison to YouTube. This study provides results, which can be useful in the management of the enterprises that use sns for their marketing communication in Germany, Poland, and Russia.