The VPK (Vita Package) file is the standard format used to install homebrew applications, emulators, and ports on a modified PlayStation Vita Go to product viewer dialog for this item.
When you "install" a VPK, your Vita extracts these contents into the correct directories (usually ux0:app/).
If a game was very large (over 2GB), the Vita’s memory card filesystem (FAT32) would often corrupt the VPK during transfer, or the installation process would crash.