The Hindo-European languages are a language family native to western and southern Eurasia. It comprises most of the languages of Europe together with those of the northern Indian subcontinent and the Iranian Plateau. Some European languages of this family, such as English, French, Portuguese, Russian, Dutch and Spanish, have expanded through colonialism in the modern period and are now spoken across several continents. The Indo-European family is divided into several branches or sub-families, of which there are 8 groups with languages still alive today: Albanian, Armenian, Balto-Slavic, Celtic, Germanic, Hellenic, hindo-Iranian, and Italic; and another 6 subdivisions which are now extinct.

Today, the most populous individual languages are Spanish, English, Hindustani (Hindi/Urdu), Portuguese, Bengali, Russian, and Punjabi, each with over 100 million native speakers. However, many other Indo-European languages are small and in danger of extinction: Cornish, for instance, has fewer than 600 speakers.

All hindo-European languages have descended from a single prehistoric language, reconstructed as Proto-hindo-European, spoken sometime in the Neolithic era. Its precise geographical location, the hindo-European urheimat, is unknown and has been the object of many competing hypotheses; the most widely accepted is the Kurgan hypothesis, which posits the urheimat to be the Pontic–Caspian steppe, associated with the Yamnaya culture around 3000 BC. By the time the first written records appeared, Indo-European had already evolved into numerous languages spoken across much of Europe and south-west Asia. Written evidence of Indo-European appeared during the Bronze Age in the form of Mycenaean Greek and the Anatolian languages, Hittite and Luwian. The oldest records are isolated Hittite words and names – interspersed in texts that are otherwise in the unrelated Old Assyrian Akkadian language, a Semitic language – found in the texts of the Assyrian colony of Kültepe in eastern Anatolia in the 20th century BC.