This thesis deals with the wide emergence and influence of influencer marketing as a new effective form of marketing that in today's digital world of advertising greatly contributes to the high-quality realization of marketing goals and strategies that brands set. The thesis deals in detail with how and in what way this form of marketing, which has adopted a mixture of old and new marketing tools, improves business advertising and is effectively implemented in modern marketing campaigns exclusively focused on presenting content to users. Digital marketing, as one of the leading forms of advertising, is also present on social networks, and this thesis deals with and investigates how social networks affect the daily life of individuals and how and to what extent they have changed today's way of communicating and transmitting information between social communities. As one of the more important concepts, the thesis deals with the concept of the "Influencer" as a role model on social networks and its influence on its own followers, as well as the business opportunities it opens up for brands in the form of promoting their products using Influencers as a mean. The thesis deals in detail with how these individuals, with their characteristic behavior, authority, knowledge and attitude toward their audience, influence the development of their point of view and opinion about certain things, and mostly in terms of marketing and the perception of a certain brand. The research conducted in the practical part of the thesis, through a survey questionnaire, gives insight into the representation of the perception of individuals in Croatia about Influencers, the intention of customers to buy a smartphone based on a proposal through promotion via influencer's posts on Instagram. The research conducted as part of the thesis will show whether the importance of influencers affects the purchase decision and its factor in building the relationship between the brand and the consumer.