The Indo-European languages are a family (or phylum) of several hundred related languages and dialects. There are about 439 languages and dialects, according to the 2009 Ethnologue estimate, about half (221) belonging to the Indo-Aryan subbranch. It includes most major current languages of Europe, the Iranian plateau, and Indian Subcontinent, and was also predominant in ancient Anatolia. With written attestations appearing since the Bronze Age in the form of the Anatolian languages and Mycenaean Greek, the Indo-European family is significant to the field of historical linguistics as possessing the second longest recorded history after the Afro-Asiatic family.

Indo-European languages are spoken by almost three billion native speakers, the largest number by far for any recognised language family. Of the twenty languages with the largest numbers of native speakers according to SIL Ethnologue, twelve are Indo-European: Spanish, English, Hindi, Portuguese, Bengali, Russian, German, Marathi, French, Italian, Punjabi, and Urdu, accounting for over 1.7 billion native speakers. Several disputed proposals link Indo-European to other major language families.