A diaspora ( dye-AS-pər-ə) is a population that is scattered across regions which are separate from its geographic place of origin. Historically, the word was used first in reference to the dispersion of Greeks in the Hellenic world, and later Jews after the Babylonian exile. The word "diaspora" is used today in reference to people who identify with a specific geographic location, but currently reside elsewhere.

Examples of notably large diasporic populations are the Assyrian–Chaldean–Syriac diaspora, which originated during and after the early Arab-Muslim conquests and continued to grow in the aftermath of the Assyrian genocide; the southern Chinese and Indians who left their homelands during the 19th and 20th centuries; the Irish diaspora that came into existence both during and after the Great Famine; the Scottish diaspora that developed on a large scale after the Highland Clearances and Lowland Clearances; the nomadic Romani population from the Indian subcontinent; the Italian diaspora and the Mexican diaspora; the Circassians in the aftermath of the Circassian genocide; the Palestinian diaspora due to the Israeli–Palestinian conflict and the broader Arab–Israeli conflict; the Armenian diaspora following the Armenian genocide; the Lebanese diaspora due to the Lebanese Civil War; the Greek population that fled or was displaced following the fall of Constantinople and the later Greek genocide as well as the Istanbul pogroms; and the emigration of Anglo-Saxons (primarily to the Byzantine Empire) after the Norman Conquest of England.

In contemporary times, scholars have differentiated the different kinds of diasporas which currently exist based on the causes of them, such as colonialism, trade/labour migrations, or the kinds of social coherence which exist within the diaspora communities and their ties to the ancestral lands; some diaspora communities maintain strong cultural and political ties to their homelands. Other qualities that may be typical of many diasporas are thoughts of return to the ancestral lands, maintaining any form of ties with the region of origin as well as relationships with other communities in the diaspora, and lack of full integration into the new host countries. Diasporas often maintain ties to the country of their historical affiliation and usually influence their current host country's policies towards their homeland.

According to a 2019 United Nations report, the Indian diaspora is the world's largest diaspora, with a population of 17.5 million, followed by the Mexican diaspora, with a population of 11.8 million, and the Chinese diaspora, with a population of 10.7 million.