Also known as… one of the most hated storage formats in video game history. For the PSP, Sony chose miniature optical discs (similar to CDs or DVDs, only tinier and encased in weird plastic coffins) over cartridges, the more familiar handheld format and what Nintendo’s used since the Game Boy. The UMDs held more data, allowing for better graphics, but the tradeoff was longer load times, noisier operation, easier to scratch games that are simultaneously harder to transport and, worst, an overall bigger, heavier system. Happily, the PS Vita corrects this error, returning games to the simpler cartridge method (technically, a Flash memory card). You’ll still have to be careful, though – these suckers are small enough to blow away in a light breeze.