The Nintendo DS[a] is a foldable handheld game console produced by Nintendo, released globally across 2004 and 2005. The DS, an initialism for "Developers' System" or "Dual Screen", introduced distinctive new features to handheld games: two LCD screens working in tandem (the bottom one being a touchscreen), a built-in microphone and support for wireless connectivity. Both screens are encompassed within a clamshell design similar to the Game Boy Advance SP. The Nintendo DS also features the ability for multiple DS consoles to directly interact with each other over Wi-Fi within a short range without the need to connect to an existing wireless network. Alternatively, they could interact online using the now-defunct Nintendo Wi-Fi Connection service. Its main competitor was Sony's PlayStation Portable during the seventh generation of video game consoles. Prior to its release, the Nintendo DS was marketed as an experimental "third pillar" in Nintendo's console lineup, meant to complement the Game Boy Advance family and GameCube. However, backward compatibility with Game Boy Advance titles and strong sales ultimately established it as the successor to the Game Boy series. On March 2, 2006, Nintendo launched the Nintendo DS Lite, a slimmer and lighter redesign of the original Nintendo DS with brighter screens and a longer lasting battery. On November 1, 2008, Nintendo released the Nintendo DSi, another redesign with several hardware improvements and new features, although it lost backwards compatibility for Game Boy Advance titles and a few DS games that used the GBA slot. On November 21, 2009, Nintendo released the Nintendo DSi XL, a larger version of the DSi. All Nintendo DS models combined have sold 154.02 million units, making it the best-selling Nintendo system, the best-selling handheld game console, and the second-best-selling video game console of all time, overall, behind Sony's PlayStation 2. The Nintendo DS was succeeded by the Nintendo 3DS in February 2011.