In the contemporary world, the importance of technology and the Internet steadily increases and the influence exerted by the social media becomes more and more apparent. As our everday life took on an online form, so did the marketing. Consequently, there have been some changes in social media users behaviour, customers behaviour and commerical activity of many companies. A multitude of various companies have noticed that many people ask for advice or recommendation before making a purchase, be it from their family or friends, or strangers on the Internet. Aforementioned, and many other, factors have brought about a new form of marketing communication known as the influencer marketing. Influencer marketing is based upon cooperation between companies and influencers, whereby influencers promote companies products or services on their social media platforms. Influencers play a very significant role in those collaborations, mostly because they positively influence the development of a brand, extend the companies range, help make products or services more easily recognizable, all of which then exerts influence on the customers decision to make a purchase. Alongside all that, the newly-emerged Generation Y, whose consumer behaviour has been influenced not only by their aim in life, education, employment and work ethics, but also by the influencers. This has been proven by the study conducted for the purposes of this master's thesis.