In the history of video games, the sixth generation era (sometimes called the 128-bit era; see "bits and system power" below) is the era of computer and video games, video game consoles, and handheld gaming devices available at the turn of the 21st century, starting on November 27, 1998. Platforms in the sixth generation include consoles from four companies: the Sega Dreamcast (DC), Sony PlayStation 2 (PS2), Nintendo GameCube (GC), and Microsoft Xbox. This era began on November 27, 1998, with the Japanese release of the Dreamcast, which was joined by the PlayStation 2 on March 4, 2000, the GameCube was later joined in September 14, 2001 and the Xbox on November 15, 2001, respectively. In March 31, 2001, the Dreamcast was among the first to be discontinued. Xbox in 2006, GameCube in 2007 and PlayStation 2 was the last, in January 2013. Meanwhile, the seventh generation of consoles started on November 22, 2005, with the launch of the Xbox 360.

The major innovation of this generation was of full utilization of the internet to allow a fully online gaming experience. While the prior generation had some systems with internet connectivity, such as the Apple Pippin, these had little market penetration and thus had limited success in the area. Services such as Microsoft's Xbox Live became industry standard in this, and future, generations. Another innovation of the Xbox was the first system to utilize an internal hard disk drive to store game data. This caused many improvements to the gaming experience, including the ability to store program data (rather than just save game data) that allowed for faster load times, as well as the ability to download games directly from the internet rather than to purchase physical media such as a disk or cartridge. Soon after its release other systems, like the Sony PlayStation 2, produced peripheral storage devices to allow similar capabilities, and by the next generation internal storage became industry standard.

Bit ratings (i.e. "64-bit" or "32-bit" for the previous generation) for most consoles largely fell by the wayside during this era, with the notable exceptions being promotions for the Dreamcast and PS2 that advertised "128-bit graphics" at the start of the generation. The number of "bits" cited in this way in console names refers to the CPU word size, and had been used by hardware marketing departments as a "show of power" for many years. However, there is little to be gained from increasing the word size much beyond 32 or 64 bits because, once this level is reached, performance depends on more varied factors, such as processor clock speed, bandwidth, and memory size.

The sixth generation of handhelds began with the release of the Bandai's WonderSwan, launched in Japan in 1999. Nintendo maintained its dominant share of the handheld market with the release in 2001 of the Game Boy Advance, which featured many upgrades and new features over the Game Boy. The Game Boy Advance was discontinued in early 2010. The next generation of handheld consoles began in November 2004, with the North American introduction of the Nintendo DS.

The last official Dreamcast games were released in 2002 (North America and Europe) and 2007 (Japan). The last GameCube games were released in 2006 (Japan) and 2007 (North America and Europe). The last Xbox games were released in 2007 (Japan) and 2008 (Europe and North America). Pro Evolution Soccer 2014 was the last game for the PlayStation 2 (in Europe), which was released in November 2013. The last PS2 game, Final Fantasy XI: Rhapsodies of Vana'diel, was released in May 2015, marking the end of this generation.