This master's thesis titled "The use of video sharing service - YouTube" was written with the aim of becoming better acquainted with this fast-growing platform, with the focus on four generations of today. Through the theoretical part is elaborated the topic of social media and its importance for society, in more detail is discussed the YouTube platform, its origins, its components and the advertising that its benefits provides. In the last chapter of the theoretical part, the focus is on the four generations of today - Baby boomers, Generation X, Generation Y and Generation Z. Apart from their characteristics and the events that shaped them, it is written about their social media habits. This is the link to the research section and it opens assumptions that will later be confirmed or refuted. The research part, through the questionnaire, seeks to become more acquainted with the habits and attitudes of the mentioned generations, which subsequently led to the conclusion of the whole research, but also gave suggestions for companies to successfully use the YouTube platform. Finally, there is the final discussion and conclusion of the whole topic and the thesis.