Sony has announced that the total worldwide "sell-in" units (so the number sold to retailers rather than what consumers have actually purchased) of the PSP, including PSP-1000, 2000 and 3000 series, has hit a total of 50 million units as of January 2009.

The first handheld platform from the PlayStation family, the PSP debuted in December 2004 in Japan, March 2005 in North America, May 2005 in Asian countries and regions, and September 2005 in Europe.

Sony says the PSP "keeps evolving" due to "exciting" software titles and "fun" peripherals as well as upgrading features through regular system software updates.

On the games front, Sony says more than 2000 titles on UMD are available worldwide, with cumulative software sell-in units reaching 200 million to date.