Overtourism has become one of the most publicized issues in contemporary tourism debates in recent years, capturing the attention of international media, local administrations, and researchers. This phenomenon, known by different names since the 1960s, describes situations where the impact of tourism exceeds the sustainability thresholds of a destination. This article focuses on the conceptual evolution of the term - from its first academic formulations to its widespread media use—while examining the various manifestations of the phenomenon and its multidimensional impacts on affected destinations. Through a systemic approach, the text also explores the opposite phenomenon of undertourism, highlighting how the solution does not lie in limiting tourist flows but in managing them intelligently.