Short answers, pulled from the story.
Nintendo announced the device under the codename Nintendo DS on the 20th of January 2004. The announcement described it as an experimental third pillar alongside the Game Boy Advance and GameCube rather than a replacement for either.
North America received the console on the 21st of November 2004 while Japan followed on December 2 with releases in Australia and New Zealand arriving on the 24th of February 2005. Europe received the console on the 11th of March 2005.
As of the 31st of March 2016 all Nintendo DS models combined have sold 154.02 million units. Combined sales including the DS Lite and DSi models surpassed 154 million units making it Nintendo's best-selling system.
On the 2nd of March 2006, Nintendo released a refreshed model called the Nintendo DS Lite which was slimmer lighter featured brighter screens and improved battery life. The top screen has a maximum brightness of 200cd/m2 while the lower touch screen reaches 190cd/m2.
The system supports Wi-Fi via the IEEE 802.11b standard enabling local multiplayer over short distances and online play through the now-defunct Nintendo Wi-Fi Connection service. Download Play allowed users to play multiplayer games with other systems using only one game card.