Xbox is a video gaming brand that consists of four main home video game console lines, as well as applications (video games), the streaming service Xbox Cloud Gaming, and online services such as the Xbox network and Xbox Game Pass. The brand is owned by Microsoft Gaming, a division of Microsoft.

The brand was first introduced in the United States in November 2001, with the launch of the original Xbox console. The Xbox branding was formerly, from 2012 to 2015, used as Microsoft's digital media entertainment brand replacing Zune. In 2022, Microsoft expanded its gaming business and reorganized Xbox to become part of its newly formed Microsoft Gaming division. Under Microsoft Gaming, Xbox's first-party publishers are Xbox Game Studios, ZeniMax Media (Bethesda Softworks), and Activision Blizzard (Activision, Blizzard Entertainment, and King), who own numerous studios and successful franchises.

The original device was the first video game console offered by an American company after the Atari Jaguar stopped sales in 1996. It reached over 24 million units sold by May 2006. Microsoft's second console, the Xbox 360, was released in 2005 and has sold 86 million units as of October 2015. The third console, the Xbox One, was released in November 2013 and has sold 58 million units. The fourth line of Xbox consoles, the Xbox Series X and Series S, were released in November 2020. The head of Xbox is Phil Spencer, who succeeded former head Marc Whitten in late March 2014.

When Sony Computer Entertainment first announced the PlayStation 2 in 1999, the company had positioned the console as a centerpiece for home entertainment, as it not only would play video games, but also could play audio CDs and video DVDs. Microsoft, whose business had been primarily in supporting the personal computer (PC) business with its Windows operating system, software, and games, saw the PlayStation 2 as a threat to the personal computer.

Four engineers from Microsoft's DirectX team—Kevin Bachus, Seamus Blackley, Ted Hase and DirectX team leader Otto Berkes, began to envision what a Microsoft console to compete against the PlayStation 2 would be like. They designed a system that would use many hardware components in common with PCs, effectively running a version of Windows and DirectX to power the games on the console. This approach would make it easy for developers on Windows to build games for their new system, differentiating itself from the custom hardware solutions of most consoles. Numerous names were suggested for this console, including "Direct X Box", and the "Windows Entertainment Project". Microsoft's marketing team conducted consumer surveys of the name, using the name "Xbox" as a control believing this would be least desirable, but found that this had the highest preference from their tests, and was selected as the name of the console.

Microsoft has been recently working to leverage the branding of "Xbox" beyond the console hardware but as a general video game brand, reflected in the renaming of Microsoft Studios to Xbox Game Studios in 2019. Phil Spencer stated in June 2019 that for Microsoft, "The business isn't how many consoles you sell. The business is how many players are playing the games that they buy, how they play." which journalists have taken as a route to de-emphasize console hardware and prioritize games, subscriptions and services for players. Later in February 2020, Spencer said that moving forward, the company does not see "traditional gaming companies" like Nintendo and Sony as their competitors but instead those that offer cloud computing services such as Amazon and Google. Spencer identified that Microsoft Azure is a major component of their plans going forward, which powers its Xbox Cloud Gaming game streaming service. Spencer also cited mobile gaming as a potential area, and where Microsoft was trying to position itself with its services should this become the more preferred form for gaming. Spencer said "I don't think it's "hardware agnostic" as much as it's 'where you want to play'", in describing how Microsoft was strategizing the Xbox branding for the future.

Microsoft announced in June 2025 that it was partnering with AMD to produce the next generation of Xbox hardware, which could take on a range of device types including consoles and computers. Amid industry rumors that Microsoft was abandoning hardware in favor of game development that emerged around Google October 2025, Xbox president Sarah Bond confirmed they had already started development work for the next console.

The original Xbox was released in North America on November 15, 2001, in Japan on February 22, 2002, and in Australia and Europe on March 14, 2002, marking Microsoft's debut in the gaming console market. As part of the sixth generation of video game consoles, the Xbox competed with Sony's PlayStation 2, Sega's Dreamcast (which stopped American sales before the Xbox went on sale), and Nintendo's GameCube. Built around a 733 MHz 32-bit Intel Pentium III CPU and a 233 MHz Nvidia GeForce 3-based NV2A GPU with 64 MB of memory, the Xbox was the first console offered by an American company after the Atari Jaguar stopped sales in 1996. Its name was derived from a contraction of DirectX Box, a reference to Microsoft's graphics API, DirectX.