Sega is a video game developer, publisher, and hardware development company headquartered in Tokyo, Japan, with multiple offices around the world. The company has produced home video game consoles and handheld consoles since 1983; these systems were released from the third console generation to the sixth. Sega was formed from the merger of slot machine developer Service Games and arcade game manufacturer Rosen Enterprises in 1964, and it produced arcade games for the next two decades. After a downturn in the arcade game industry in the 1980s, the company transitioned to developing and publishing video games and consoles. The first Sega console was the Japan-only SG-1000, released in 1983. Sega released several variations of this console in Japan, the third of which, the Sega Mark III, was rebranded as the Master System and released worldwide in 1985. They went on to produce the Genesis—known as the Mega Drive outside of North America—and its add-ons beginning in 1988, the Game Gear handheld console in 1990, the Sega Saturn in 1994, and the Dreamcast in 1998.
Sega was one of the primary competitors to Nintendo in the video game console industry. A few of Sega's early consoles outsold their competitors in specific markets, such as the Master System in Europe. Several of the company's later consoles were commercial failures, however, and the financial losses incurred from the Dreamcast console caused the company to restructure itself in 2001. As a result, Sega ceased to manufacture consoles and became a third-party video game developer. The only console that Sega has produced since is the educational toy console Advanced Pico Beena in 2005. Third-party variants of Sega consoles have been produced by licensed manufacturers, even after production of the original consoles had ended. Many of these variants have been produced in Brazil, where versions of the Master System and Genesis are still sold and games for them are still developed.