- U2W (Ultra2 Wide SCSI)
- UA (User Agent)
- UA (User Area)
- UAAG (User Agent Accessibility Guidelines)
- UAC (User Account Control)
- UAM (User Authentication Method)
- UART (Universal Asynchronous Reveiver-Transmitter)
- UBR (Unspecified Bit Rate)
- UCD (Uniform Call Distribution)
- UCE (Unsolicited Commercial Email)
- UCP (Unified Control Plane)
- UCR (Undercolour Removal)
- UCS (Unicode Conversion Support)
- UCS (Universal Character Set)
- UCS (User Coordinate System)
- UCSD (University of California San Diego)
- UCT (Universal Coordinated Time)
- UDC (User Defined Command)
- UDDI (Universal Description, Discovery and Integration)
- UDE (Universal Data Exchange)
- UDEC (Universal Digital Electronic Computer)
- UDF (Universal Disk Format)
- UDMA-4
- UDMA-5
- UDMA/33 (Ultra DMA/33)
- UDP (User Datagram Protocol)
- UDRP (Uniform Domain Name Dispute Resolution Policy)
- UFS (UNIX File System)
- UFS (Unix File System)
- UG (User Group)
- UHF (Ultra High Frequency)
- UIC (User Identification Code)
- UIMS (User Interface Management System)
- Uitbreidingsslot
- Uitloggen
- ULA (Uncommitted Logic Array)
- ULSI (Ultra Large Scale Integration)
- Ultra ATA/33
- Ultra ATA/66
- Ultra SCSI
- Ultra2 Wide SCSI
- Ultra3 Wide SCSI
- UltraWide SCSI
- Ultrix
- UMA (Uniform Memory Access)
- UMA (Upper Memory Area)
- UMB (Upper Memory Blocks)
- UMCS (Unattended Mode Control System)
- UMD (Universal Media Disk)
- UML (Unified Modeling Language)
- UMTS (Universal Mobile Telecommunication System)
- Unbalanced line
- UNC (Universal Naming Convention)
- Undernet
- Underscore
- Undisclosed recipients
- Undo
- Unicasting
- Unicode
- Uninstall
- UNIVAC (Universal Automatic Computer)
- Universal Turing machine
- UNIX (UNIversal eXecutive)
- UNL (Universal Network Language)
- UNMA (Unified Network Management Architecture)
- Unsubscribe
- Unzippen
- UPC (Universal Product Code)
- Upgrade
- Uploaden
- UPnP (Universal Plug and Play)
- Upper case
- UPS (Uninterruptable Power Supply)
- Uptime
- URC (Uniform Resource Characteristics)
- UREP (Unix RSCS Emulation Protocol)
- URL (Uniform Resource Locator)
- USB (Universal Serial Bus)
- USB 2.0 (Universal Serial Bus 2.0)
- USB-hub (Universal Serial Bus Hub)
- USB-Stick
- Usenet
- User-ID
- Username
- USM (UltraSonic Motor)
- USM (UnSharp Mask)
- USOC (Universal Service Ordering Code)
- USR (US Robotics)
- UTI (Universal Text Interchange)
- Utility
- UTP (Unshielded Twisted Pair)
- UTRAN (UMTS Terrestrial Radio Access Network)
- UUCP (Unix to Unix CoPy)
- UUdecode (Unix-to-Unix decoding)
- UUencode (Unix-to-Unix encoding)
- UUNET
- UWR (Ultra Wideband Radio)
- UXGA (Ultra Extended Graphics Array)
