Glossary of Internet Terms

©2007 by Walt Howe

Select the first character of the term you want to look up or use the Search link below.

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Letter X

X.25
An international standard for packet switching, typically used with older telephone networks for data communications. See frame relay .
X.500
A directory access protocol to enable a common standard for directories of information over a network. It has never caught on as well as its designers intended. See LDAP.
xDSL
See DSL.
XHTMLtm
eXtensible HyperText Markup Language. HTML re-written as an application of the XML language. See the W3C Working Draft: Building XHTML Modules
XML
Acronym for eXtensible Markup Language. A richer subset of SGML than HTML. It is a next step in the evolution of web data formats beyond HTML. See the World Wide Web Consortium (W3C) XML Page.
xmodem
An early form of file transmission for dialup and telnet connections. It is slower and uses smaller blocks of data (128 bits) than ymodem and zmodem.

XSL
Acronym for eXtensible Stylesheet Language, a style sheet companion to XML.

(last updated 15 June 2025)