Uncertainty
Unicode
Uniform resource locator [URL]
Uninterruptible power supply [UPS]
Unit testing
"Universal description, discovery and
integration" [UDDI]
Universal Serial BUS [USB]
UNIX
Untrustworthy host
Uploading

User awareness
User Datagram Protocol [UDP]
User interface impersonation
User mode
User provisioning
Utility programs
Utility script
Utility software