Nowadays the internet has drastically changed the advertising industry, and it continues to change as new technology and platforms are released. The success of any advertisement campaign lies in reaching the right class of target audience and eventually convert them as potential customers in the future. In the last few years we can notice a considerable growth of the market of online advertising, which becomes very important, and provides a major source of advertising revenue. In order to measure a campaign effectiveness there exist a variety of metrics and one of them is Click-Through Rate (CTR): a ratio showing how often people who see an advertisement end up clicking it.