The PlayStation 2, or PS2, is a sixth-generation home console designed to play videogame and other media DVDs and CDs. It is the best-selling console of all time as of 2010, with over 147 million units sold. It is backwards compatible with PlayStation games, although PlayStation games must be saved to a PlayStation memory card. It uses an upgraded, lighter version of the Dualshock gamepad, which features six face buttons, four directional face buttons, four shoulder buttons, two analog sticks, and force feedback. It supports online play through an adapter or integrated into the upgraded slimeline models, which are thinner and quieter than the original models but do not support an internal HDD.