With the rapid development of technology and popularity of the Internet and social media, the way people communicate and the language they use seem to be changing faster than ever. The research presented in this paper was conducted in order to learn about the ways teenagers and young adults in Croatia use language on the Internet; more specifically, how they use hashtags and abbreviations on popular social network sites (Facebook, Instagram and Twitter). 160 respondents provided insight into the language used in communication on the Internet. The results show that teenagers and young adults use SNSs on a daily basis, that they are familiar with the terms hashtag and abbreviation, and that they use these ‘tools’ in online interaction. The paper is divided into seven sections. Apart from the introduction and the conclusion, section two and three give information about what exactly hashtags and abbreviations are, and describe the three SNSs – Facebook, Instagram and Twitter. Furthermore, section four describes the methodology of the research, whereas section five discloses graphic presentation of the results. Section six represents a discussion of the results and includes a suggestion for possible future research in this area.