The differences between HTML and XHTML are small. As the rules of XHTML are based on those of XML, the same exceptionally strict rules apply as with XML. The major differences are outlined below.

The most important difference between the two markup languages is that HyperText Markup Language, or HTML, is an application of SGML (Standard Generalized Markup Language)1 and allows an author to omit certain tags and use attribute minimization. The Extensible HyperText Markup Language, or XHTML, is an application of XML (Extensible Markup Language). It doesn’t permit the omission of any tags or the use of attribute minimization. XHTML documents must start with an XHTML DocType declaration....

SSI stands for “server-side include,” a type of HTML instruction telling a computer that serves Web pages to dynamically generate data, usually by inserting certain variable contents into a fixed template or boilerplate Web page. Used especially in database searches. In order to use Server Side Includes, your server must be configured to support them.

SSI can help make your pages more responsive and can even help make maintaining your site an easier task. SSI is primarily used to “paste” the contents of one or more files into another. For example, a file (of any type, .html, .txt, etc.) containing a daily quote could be included into multiple SSI-enabled pages throughout a website by placing the following code into the desired pages:...

URL is an acronym for Uniform Resource Locator and is a reference (an address) to a resource on the Internet. The unique address of any Web document. The following is an example of a URL which addresses the Java Web site hosted by Sun Microsystems:

The Extensible Hypertext Markup Language, or XHTML, is a hybrid between HTML and XML that is more universally acceptable in Web pages and search engines than XML. Both standards are powerful, but XHTML is significantly better than HTML.

XHTML uses three XML namespaces (used to qualify element and attributes names by associating them with namespaces identified by URI references. Namespaces prevent identically custom-named tags that may be used in different XML documents from being read the same way), which correspond to three HTML 4.0 DTDs: Strict, Transitional, and Frameset. ...

Wiki is a piece of server software that allows users to freely create and edit Web page content using any Web browser. Wiki supports hyperlinks and has a simple text syntax for creating new pages and crosslinks between internal pages on the fly.

Wiki is a term meaning “quick” in Hawaiian, that is used for technology that gathers in one place a number of web pages focused on a theme, project, or collaboration. Wikis are generally used when users or group members are invited to develop, contribute, and update the content of the wiki....

RSS is the short for Really Simple Syndication, also known as Rich Site Summary). RSS refers to a group of XML based web-content distribution and republication (Web syndication) formats primarily used by news sites and weblogs (blogs). Any website can issue an RSS feed. By subscribing to an RSS feed, you are alerted to new additions to the feed since you last read it. In order to read RSS feeds, you must use a “feed reader,” which formats the XML code into an easily readable format (feed readers are to XML and RSS feeds as web browsers are to HTML and web pages.

An RSS document, which is called a “feed”, “web feed”, or “channel”, contains either a summary of content from an associated web site or the full text. RSS makes it possible for people to keep up with their favorite web sites in an automated manner that's easier than checking them manually....