- u
- u up
- U-L
- U2
- u4e
- u8
- UAYA
- UBS
- UCE
- UCWAP
- UDH82BME
- UDK
- UDM
- UFN
- UFUF
- UG2BK
- UGC
- UGFSU
- UGTR
- ultra-wideband
- ultraviolet data
- umfriend
- UMK
- UMTS
- UN*X
- under construction
- under mouse arrest
- underling
- UNF
- unfriend
- unicorn
- uninstalled
- unique user
- Unix
- unknown zone
- unlock
- unmetered
- unofficial site
- UNOIT
- unPC
- unplugged
- unstructured data
- unsubscribe
- UNT
- UNTCO
- unzip
- UOK
- up
- UPC
- upgradathon
- upgrade
- upgrade fever
- upgrade path
- uplink
- upload
- UPOD
- upside
- upskirting
- upstream
- ur
- UR2K
- URAPITA
- URI
- URL
- URL tagging
- URN
- URSAI
- URW
- URWS
- URYY4M
- URZ
- USB
- USC
- USCWAP
- Usenet
- user
- user agent
- user session
- user-friendly
- user-generated content
- username
- Using a previously cached copy version
- USP
- utility
- utility computing
- UTM
- UUEE
- UUENCODE - UUDECODE
- UV
- UWIWU
- UWM
- UX
