U3-compliant USB flash drives allow users to store data and install certain Windows applications on these drives. In 2004, two USB flash drive manufacturers, M-Systems and SanDisk, joined forces to form a company called U3. U3-compliant flash drives come with an application known as the U3 Launchpad. When a user connects a U3 flash drive to a Windows-based computer, he can launch an application on the drive through the U3 Launchpad interface.
When launching a U3-compliant application from a U3 flash drive, the application loads the system files that it needs. It can also write files and make changes to the registry information on the computer. When disconnecting the U3 flash drive from the computer, the application remove the information from the computer. All settings and customizations remain with the application on the U3 flash drive.
Software vendors who planned to create U3-compliant applications include ICQ, Skype, Trend Micro, Zone Labs and Ulead Systems. Other than SanDisk, other USB flash drive manufacturers including Kingston, Memorex and Verbatim also showed interest in the U3 platform.
However, the U3 technology faced various problems including incompatibility issues with some embedded system and slowness issues with certain Windows drivers. In 2009, SanDisk began to phase out support for the U3 technology and U3 applications were no longer available for download.