X
X-Modem
X.25
X.29
X.400
X.500
X.509
X/Open
X2
X86-32
X86-64
xD-Picture Card
XDE - eXtended Detail Enhancement
Xenix
Xeon
XF - eXtended Format
XG - eXtended General midi
XGA - eXtended Graphics Array
XGP - eXternal Graphics Platform
XHTML - Extensible Hypertext Markup Language
XLR
XML - eXtensible Markup Language
XMS - eXtended Memory Specification
XON/XOF
XOT
XPath - XML Path language
XPG - X/Open's Portability Guide
XQL - XML Query Language
XSL - Extensible Stylesheet Language
XSLT - XSL Transformation
XT - eXtended [or eXTended] Technology
XXencode / XXdecode
XXX
XXX password