Thanks to the many developments taking place in the mediascape, audiovisual translation in general, and subtitling in particular, have witnessed an exponential growth in academic as well as commercial interest in recent decades. This chapter sets out to contribute a detailed account of the practice of subtitling and, after proposing a definition of this multimodal professional activity, it engages in the exploration of the multiple spatial and temporal constraints that are characteristic of this form of translation. The article then offers a classification and examination of the various types of subtitles existence and, in the last section, it critically scrutinises the main translational challenges of subtitling, including the concurrent presence of source and target texts as well as the endeavour of rendering speech into written text.