A personal digital assistant or PDA is a handheld computer, also known as a palmtop computer. The latest PDAs also have both color screens and audio capabilities, enabling them to be used as mobile phones or smartphones, web browsers, or portable media players. Many PDAs can access the Internet, intranets or extranets via Wi-Fi, or Wireless Wide-Area Networks (WWANs). Almost all PDAs now employ touch screen technology and the vast majority of all PDAs sold nowadays are smartphones, with over 150 million units sold. While non-phone ("stand-alone") PDAs sell only about 3 million units per year. The RIM Blackberry, the Apple iPhone and the Nokia N-Series are typical smartphones.