X 400
X.400 was originally published in 1984 by ccitt and later re-written in 1988 jointly by iso and ccitt. X.400 is a standard that conforms to layer 7 of the osi and is a standard used for transporting e-mail messages. X.400 is an alternative standard to the commonly used smtp and includes support for several transport connections including ethernet, tcp/ip, and dial-up.
Xhtml
Xhtml is short for extensible hypertext markup language. Xhtml is a hybrid between xml and html and designed for network devices as a method of displaying web pages on network and portable devices. Xhtml was first released on January 26, 2000.
Xml
Xml is short for extensible markup language. Xml is a specification developed by w3c starting with the recommendation on february 10, 1998. Xml is similar to html, xml uses tags to markup a document, allowing the browser to interpret the tags and display them on a page. Unlike html, xml language is unlimited (extensible) which allows self-defining tags and can describe the content instead of only displaying a page’s content. Using xml other languages such as rss and mathml have been created, even tools like xslt were created using xml.
Xmpp
Xmpp which stands for extensible messaging and presence protocol, is a communications protocol for messaging systems. It is based on xml, storing and transmitting data in that format. It is used for sending and receiving instant messages, maintaining buddy lists, and broadcasting the status of one’s online presence. Xmpp is an open protocol standard. Anyone can operate their own xmpp service, and use it to interact with any other xmpp service. The standard is maintained by xsf, the xmpp standards foundation.
Xmt
Xmt is also called transmit. Xmt is the method of sending data to an alternate computer or device.
Xns
Xns is short for xerox network services, xns is a proprietary network communications protocol developed by xerox. Xns is no longer used and has been replaced by transmission control protocol / interface program (tcp/ip).