OUI

OUI is an acronym that can refer to more than one concept, depending on the context. In computing and networking, it most commonly denotes Organizationally Unique Identifier, a 24-bit number assigned by the IEEE Registration Authority to identify a device manufacturer. The OUI forms the first three octets of most MAC addresses, with the remaining bits used to identify a specific device within that vendor’s range. OUIs are registered and publicly listed by IEEE, and they are essential for identifying the origin of network hardware in Ethernet, Wi-Fi, and other MAC‑address-based technologies. The concept also extends to Extended Unique Identifiers used in IPv6 addressing, such as EUI-64, which can incorporate an OUI or an extended form of it.

Beyond computing, OUI is not widely used as a general acronym in everyday technical language. When written as oui (lowercase) in French, it is the word for “yes.” This usage is unrelated to the IEEE designation and is part of standard vocabulary in French-speaking regions, as well as in language learning and cultural contexts. The term appears in literature, dialogue, and branding where the French meaning is relevant or evocative.

In summary, OUI most commonly refers to the Organizationally Unique Identifier in MAC addressing, serving as a vendor identifier within the broader address structure. It also appears as the French word for “yes” in non-technical contexts, illustrating how the same letter combination can carry distinct meanings across domains.