The Validator is based on Open SP, an SGML parser based on James Clark's SP SGML parser.
The Validator itself is a CGI script that (basically) fetches your document, passes it through the parser, and post-processes the resulting error list for easier reading. Most probably, you will want to use the online Markup Validation service.
Most pages on the World Wide Web are written in computer languages (such as .
However, Just as texts in a natural language can include spelling or grammar errors, documents using Markup languages may (for various reasons) not be following these rules.
If, for some reason, you prefer running your own instance of the Markup Validator, check out our developer's documentation.
The output of the Markup Validator may be hard to decipher for newcomers and experts alike, so we are maintaining a list of error messages and their interpretation, which should help. Did The Validator complain about your , and make sure it correctly identifies the type of HTML you're using.
The process of verifying whether a document actually follows the rules for the language(s) it uses is called .
With these concepts in mind, we can define "markup validation" as the process of checking a Web document against the grammar (generally a DTD) it claims to be using.
There are other possible uses and a few usage options, please read the user's manual for further help with this service.
Validity is one of the quality criteria for a Web page, but there are many others.