The diploma thesis "The impact of blogs on the consumer behaviour of the selected target group" was created in order to find out how blogs can influence consumer-shopping decision-making process. The theoretical knowledge about advertising, consumer behaviour, and blog writing, which are explained in the first part of the paper, was then applied to the practical part where we surveyed the respondents' opinion, especially the target audience of 18-25 year old young people, on the impact of blogs particularly on their consumer behaviour. At the end of the diploma thesis, we summarized the achieved results and the evaluation of the hypotheses which we set.