The Universal Media Disc was developed by Sony as the proprietary optical format for the PlayStation Portable (PSP), which launched in Japan in December 2004. It consists of a 60 mm disc inside a plastic cartridge measuring roughly 64 mm × 63 mm × 4.2 mm1). A dual-layer UMD holds up to 1.8 GB, enough for a full PSP game or a feature-length movie. Single-layer discs were also produced and had a capacity of 900 MB.
Unlike most other DBEM formats, UMD is a read-only, pre-pressed format: discs are stamped at the factory like a CD or DVD, and consumer drives cannot record to them. Besides games, Sony and several studios released movies, TV episodes, and music videos on UMD. The format faded quickly as downloads took over, and the digital-only PSP Go (2009) dropped the UMD drive entirely.