Which PlayStation handheld used the Universal Media Disc as its physical game format?

The PlayStation Portable used the Universal Media Disc as its physical game format.

Sony designed the Universal Media Disc, or UMD, as a small optical disc housed inside a protective cartridge. The format could store up to 1.8 gigabytes, giving the PlayStation Portable more capacity than many contemporary handheld cartridges and supporting games, movies, and other media.

The original PlayStation Portable launched in Japan in December 2004 and later reached other major regions in 2005. A UMD slid into a drive on the back of the handheld, while downloadable games could also be stored on Memory Stick media.

PlayStation Vita, the PSP's successor, did not use UMD. It used proprietary Vita game cards instead, and the later PSP Go removed the UMD drive entirely. Those differences are why the UMD format is specifically associated with the original PlayStation Portable family rather than every Sony handheld.