One of the several possibilities that the internet provides is the extent to which the notion of expertise has shifted from the realm of professionals and is now more distributed among everyday people. In this thesis, I examine three websites where people get together to discuss cinema: a platform that gathers people from around the world (IMDb), a regional site (Netflix Latin America) and a local one (HiFi Chile). By presenting themselves as experts through their language use, these online reviewers emphasise an aspect of their identities, which is constructed within a process of interactive negotiation, i.e., the reviews are taken up either textually or through the use of the affordances that the sites provide. In this study, I employ a mixed-method approach that combines digital ethnography, software-assisted manual coding, narrative analysis, and corpus linguistics. A noticeable pattern in language use among these online reviewers is the prominence of references to genre and personal experience. Firstly, reviewers tend to show their knowledge of specific cinematic categories, an aspect that plays a key role within their evaluations. Secondly, users show a tendency to tell ‘small stories’ about their film-watching experience, which sometimes involve them revisiting certain productions and not only changing their perceptions of these movies, but also narrating transformations in their own lives between each viewing. Overall, users in the data show how knowledgeable they are, as opposed to telling others how much they know about cinema (e.g., by boasting about being experts). With this thesis, I intend to contribute to research on language and new media, especially within an area that remains largely unexplored such as online reviews and the ways in which posts of this kind show discursive constructions of expertise. This research also adds to the existing studies that look at narratives on online platforms, particularly when it comes to Spanish-speaking people who use stories in order to express their identity.