This paperwork topic is Online advertising and consumer buying behaviour. The intention is to theoretically explain online advertising and how it affects customers. The theoretical part of this paperwork defines marketing communication and it’s forms with an emphasis on online advertising, customer behaviour and factors that influence customer behaviour. In the continuation of this paperwork, the buying behaviour of customers in online environment is explained using the terms such as: buyer journey, buyer persona and content marketing. The last part of this paperwork defines generation cohorts and their characteristics so readers can easily understand the research on the topic of Internet buying behaviour based on generation cohorts in the Republic of Croatia. The research was conducted on a sample of 135 respondents using Google Forms platform. The questionnaire consisted of eight questions that determined the frequency of purchases via the Internet and the importance of the appearance and content of Internet sites, while the two last questions in the questionnaire were related to the age and gender of respondents. The research established that Internet shopping is on the rise, which was the impact of the COVID-19 pandemic, and that the aesthetic and informative part of the website is extremely important. However, it is important to note that certain generation cohorts were in minority so it would be desirable to repeat the research on that generation cohorts. The conclusion of the research and the overall paperwork is that Internet shopping is the future of shopping, especially for younger generations, and marketers and businesses must be prepared to keep up with technology and upgrade their business in an online environment.