duo

Duo is a term that denotes a pair of people or things that function or are presented as a unit. The word originates from Latin duo, meaning two, and is used across languages and domains to signal a two-person combination or collaboration.

In music and performing arts, a duo refers to an ensemble or performance for two musicians or performers. A musical duo can feature two vocalists, two instrumentalists, or a singer and an instrumentalist, performing together as a cohesive unit. The repertoire ranges from classical duets to contemporary arrangements and can be written specifically for two performers or improvised.

In technology and consumer services, Duo appears as the name of several products and brands. Google Duo was a video calling service introduced by Google to enable simple, high-quality calls across devices; it supported one-to-one and group video calls and was designed for cross-platform use on Android, iOS, and the web. Duo Security is a cybersecurity company that provides two-factor authentication and access security solutions for organizations; it offers methods such as push-based prompts and hardware-backed codes and became part of Cisco Systems through a 2018 acquisition. The use of the word in these contexts signals a two-person or two-factor focus, aligning with the core meaning of two.

Beyond products, “duo” is a general descriptor for any pairing or collaboration of two entities, often highlighted for its complementary or joint nature. In practice, the term is versatile and widely applied in music, media, technology, and everyday language.