Short answers, pulled from the story.
Nintendo publicly announced the GameCube on the 12th of May 1999 during a press conference. The announcement revealed the codename Dolphin and strategic partnerships with IBM for the PowerPC-based CPU known as Gekko.
The GameCube sold 22 million units worldwide, achieving a 13% market share that tied with the Xbox but fell well below the 60% held by the PlayStation 2. By the 31st of March 2003, only 9.55 million units had been sold, which was short of Nintendo's initial goal of 10 million consoles.
IBM designed the 32-bit PowerPC-based processor known as Gekko while ArtX created the system logic and graphics processor before being acquired by ATI Technologies. Matsushita Electric Industrial, now Panasonic Corporation, developed the proprietary miniDVD optical disc format used in the console.
Successful exclusives included Star Wars Rogue Squadron II: Rogue Leader from Factor 5 and Resident Evil 4 from Capcom. Other notable titles include the Pikmin series, Chibi-Robo!, Metroid Prime, and Luigi's Mansion which became popular franchises after debuting on the system.
Nintendo announced it had ceased first-party support for the GameCube in February 2007 with the final game released on the 14th of August 2007. The company launched the Wii successor on the 19th of November 2006 in North America to replace the aging console.