The term "fake news" has become ubiquitous in contemporary political and legal discussions. In this scenario, legal and judicial disputes are multiplied around the limits of freedom of expression. However, despite the definitive entry of the term into the Brazilian and global political lexicon, there are still many gaps in our understanding of what the term means and what its possible harmful impacts are. This article seeks to fill, albeit partially, this gap, conducting a bibliographic review on what fake news means and about what its possible consequences in the psychological and political spheres means. Our study points out that, in order to advance the regulation and the debate on the subject itself, we need to have conceptual clarity about what fits and what does not fit the concept of fake news, and we also need to apply legal measures that are proportional to its impacts.