The Nintendo DS (DS for Dual Screen) is a handheld device produced by Nintendo in 2004. The system has a very good reputation for its unique ability of having two screens (hence the name). The device has since become the most sold handheld of all time.
The DS was released in Japan and the United States in November and December 2004, and elsewhere in 2005. The launch title for the game as none other than Super Mario 64 DS, albeit not being the most popular game.
The DS had many great titles that are worth checking out, but these don't need to be mentioned here.
The DS (original) was two screens held together by hinges. The top one was where the main game took place (usually) and had no buttons. The bottom part was home to the buttons, which were the D-Pad, the A/B/X/Y configuration, and other buttons. The color could vary, but the one in the article picture is grey, the default color.