The Iranian languages (also called Iranic languages) form a subfamily of the Indo-Iranian languages which in turn are a subgroup of the Indo-European language family. The speakers of Iranian languages are known as Iranian peoples.

The Iranian languages are considered in three stages of Old (until 400 BCE), Middle (400 BCE – 900 CE), and New (since 900 CE). From the Old Iranian languages the better understood and recorded ones are Old Persian (a language of Achaemenid Iran) and Avestan (the language of Zarathushtra). Middle Iranian languages included Middle Persian (a language of Sassanid Iran) and Parthian (a language of Arsacid Iran). There are many Iranian languages, the largest amongst them are Persian, Pashto, Kurdish, and Balochi.

Today, there are an estimated 150–200 million native speakers of Iranian languages. The Ethnologue lists 87 Iranian languages.Persian has about 65 million native speakers, Pashto about 50 million, Kurdish about 18 million, Balochi about 7 million, and Lurish about 2.3 million.

The Iranian peoples (Iranic peoples) are an Indo-European ethnic-linguistic group that comprise the speakers of Iranian languages, a major branch of the Indo-European language family, as such forming a branch of the Indo-European-speaking peoples. Their historical areas of settlement were on the Iranian plateau, and comprised most of Iran and certain areas of Central Asia such as Tajikistan and Uzbekistan and most of Afghanistan, some parts of western Pakistan, northern Iraq and eastern Turkey, and scattered parts of the Caucasus Mountains. Their current distribution spreads across the Iranian plateau, and stretches from Pakistan's Indus River in the east to eastern Turkey in the west, and from Central Asia and the Caucasus in the north to the Persian Gulf in the south – a region that is sometimes called the Iranian cultural continent, or Greater Persia by scholars, and represents the extent of the Iranian languages and influence of the Persian People, through the geopolitical reach of the Persian empire.

The Indo-Iranian language group constitutes the easternmost extant branch of the Indo-European family of languages. It consists of three language groups: the Indo-Aryan, Iranian and Nuristani. The Indo-Iranian languages occasionally go by the term "Aryan languages." The speakers of the Proto-Indo-Iranian language, the hypothetical Proto-Indo-Iranians, are usually associated with the late 3rd millennium BC Andronovo and Sintashta-Petrovka cultures of Central Asia. Their expansion is believed to have been connected with the invention of the chariot.

The contemporary Indo-Iranian languages form the largest sub-branch of Indo-European, with more than one billion speakers in total, stretching from Europe (Romani) and the Caucasus (Ossetian) eastward to Xinjiang (Sarikoli) and Assam (Assamese) and south to Sri Lanka (Sinhalese). SIL in a 2005 estimate counts a total of 308 varieties, the largest in terms of native speakers being Hindustani (Hindi and Urdu, ca. 190-330 million), Bengali (ca. 190 million), Punjabi (ca. 88 million), Marathi (ca. 70 million), Persian (ca. 70 million), Pashto (ca. 50 million), Gujarati (ca. 46 million), Kurdish (ca. 16-30 million), Bhojpuri (ca. 35 million), Awadhi (ca. 35 million), Maithili (ca. 35 million), Oriya (ca. 32 million), Marwari (ca. 31 million), Sindhi (ca. 21 million), Rajasthani (ca. 20 million), Chhattisgarhi (ca. 17 million), Assamese (ca. 17 million), Sinhalese (ca. 16 million), and Rangpuri (ca. 15 million).