This paper focuses, firstly in the context of early communication theories and including the contemporary analysis of personal influence, on the position of influencers within the traditional media, and its analogy to the position they take in the area of the new media. The historical review is followed by different definitions of influencers as well as theories that emphasize their importance in communicating information and shaping the opinions of those who they influence. In modern times, influencers are recognized as important contributors to the transmission of advertising messages, so this paper also focuses on the analysis of influencers on social networks, illustrating by concrete examples their growing position in the context of a new media which results in lucrative marketing co-operations. This paper also presents available figures and performance analysis, as well as an overview of available tools for such analysis. The paper concludes that word of mouth is an extremely effective method of reaching the target audience, which is why brands are increasingly turning to niche marketing by sending their messages through selected influencers.