The World Wide Web Consortium, also referred to as the W3C, is a group that creates standards for web technologies. Members come from a range of organisations including Google, Microsoft Corporation, Yahoo Inc, MSN, Adobe, Mozilla Foundation, Apple Inc and AOL LLC.

Since 1994, this group of people have shaped the way we design pages for the web using such standards as the various versions of HTML, protocols such as HTTP and FTP, and CSS (to name only a few of the many technologies they are involved in). As web developers, we are guided to an extent by how browsers react to code, and the browsers differ in the way that they render standard code.

The most important work done by the W3C is the development of Web specifications (called “Recommendations”) that describe communication protocols (like HTML and XML) and other building blocks of the Web.

Most pages on the World Wide Web are written in computer languages (such as HTML) that allow Web authors to structure text, add multimedia content, and specify what appearance, or style, the result should have.

As for every language, these have their own grammar, vocabulary and syntax, and every document written with these computer languages are supposed to follow these rules.

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. The process of verifying whether a document actually follows the rules for the language(s) it uses is called validation, and the tool used for that is a validator. A document that passes this process with success is called valid.

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.

To make the web site search engine friendly, Your Firm Online uses W3C standards to check your website page by page.

Use http://validator.w3.org/ to check the markup (HTML, XHTML, …) of web documents.