A growing percentage of this content consists of reaction videos, a new type of user- generated content that has been on the rise within this social media platform, in which individuals record themselves reacting to any sort of content. This paper aims to explore the dynamics involved in this type of content, not only from the perspective of the creator but also from the angle of the viewer, to try and understand what leads to the popularity of these videos. The current thesis aims not only to dissect the topic but also to present the field of Media and Communication studies with relevant and unprecedented insight into the motivations that lead viewers to engage with this kind of content and contribute to debunk this contemporary audience phenomenon. To do so, a case study was conducted on a YouTube channel named ‘REACT’. The study utilised Uses and Gratifications Theory as well as the concept of mediated voyeurism to help contextualise the reaction genre. Using content analysis, 4 of their videos were analysed qualitatively. Plus, a focus group was conducted in order to not only understand the overall sentiment towards the reaction video genre, but also identify the possible reasons for it to be a global success. Results show that reaction videos can be characterised as dynamic, highly engaging and extremely relatable videos. Furthermore, they can be of amateur nature – unscripted, spontaneous and organic, or more professionalised – scripted and edited. Additionally, while most of the needs these videos fulfil can be categorised as diversion needs, the remaining ones can be perceived as both personal identity and surveillance needs. The current research can be seen as a useful tool for society to interpret relevant patterns of content creation and consumption within the current digital age.