About The W3C Markup Validation Service
The Markup Validator is a free service by W3C that helps check the validity of Web documents.
The majority of the Internet documents are created with the help of special markup languages, in particular HTML and XHTML. To define the languages, the technical specifications are required. The technical specifications usually consist of the softcopy formal grammar (and vocabulary). The Markup Validator is a special device that helps to provide the process that implies the verification of a document and the above-mentioned constraints.
Validating service is a quick and economic way to improve and secure the quality of the Web document. However, the validation act does not imply the full checking for conformance to the specification.
The validator gives the possibility to handle the documents that were written in almost all markup languages. The validator supports the documents of the HTML and XHTML family, MathML, SMIL and SVG. The SGML or XML DTD Web documents that can be verified with the help of the Markup Validator in the case if the proper typed language was used.
This validator belongs to An HTML verifying system that corresponds to International Standard ISO/IEC 15445—HyperText Markup Language, and International Standard ISO 8879—Standard Generalized Markup Language (SGML). Therefore, the validator verifies in compliance with the above-mentioned ISO standards and possesses the W3C recommendations.