IFF explained

IFF, Iff or iff may refer to:

People and characters

Iff of the Unpronounceable Name, a fictional character in The Riddle-Master trilogy by Patricia A. McKillip
Simon Iff, a fictional character by Aleister Crowley

International film festival, a type of film festival
Indonesian Film Festival, an annual film festival in Indonesia
Ischia Film Festival, an annual film festival held on the island of Ischia, Italy
Inferno, Flame, and Flint, a software by Autodesk Media and Entertainment
"IFF", an episode of The Expanse

Identification friend or foe, an electronic radio-based identification system for the military
If and only if, a biconditional logical connective between statements, where either both statements are true or both are false
Iff card, a smart card used on bus services in Cardiff, Wales, United Kingdom
Interchange File Format, a computer file format

International Fencing Federation (Fédération Internationale d'Escrime or FIE), the international governing body for fencing
International Floorball Federation, the global governing body for the sport of floorball
Irish Fencing Federation, the governing body for fencing in Ireland

Iff Books, an imprint of John Hunt Publishing
Independent Fianna Fáil, a political party in Ireland
Institute For Figuring, an organization that promotes the public understanding of the poetic and aesthetic dimensions of science, mathematics and the technical arts
International Federation of Factory Workers, former trade union international
International Flavors & Fragrances, an American corporation which produces flavors and fragrances
International Freedom Foundation, a self-described anti-communist group established in Washington, D.C.
Fakultät für Interdisziplinäre Forschung und Fortbildung (Faculty for Interdisciplinary Research and Continuing Education), a faculty of the Austrian University of Klagenfurt

Illicit financial flows, a concept in economics and finance related to resources that are of illegal origin, use or transfer
International Finance Facility, proposed by HM Treasury in conjunction with the Department for International Development of the United Kingdom
International freight forwarder, an individual or company that books or otherwise arranges space for shipments between countries via common carriers
Utaha language (ISO 639 language code iff), also known as Ifo, an extinct language from Erromango, Vanuatu