What are these W3C Buttons?

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The W3C is the World Wide Web Consortium, the organization responsible for
the technical underpinnings of the World-Wide Web. It creates and maintains
standards for the various technologies that web developers use to create websites.

For example,

• HTML (standing for HyperText Markup Language) and
• CSS (standing for Cascading Style Sheets),

both of which are basic tools for creating web pages.

The W3C buttons signify that the author of the page claims to have validated the coding of the page to ensure that it conforms with the appropriate W3C specifications.

The presence of the buttons does not in fact prove anything, it merely suggests that the author wishes to present herself or himself as conscientious and technically aware. However, these buttons do provide a means whereby, should you so wish, you can verify the author’s claim!

There is an excellent reason for making sure that pages pass validation, and that is to ensure conformity of rendition. All web browsers render valid pages in a pretty uniform fashion, so that the displayed page has a high probability of conforming to what the author intended. When a page contains invalid content, browsers make a best guess at what the author intended, but each browser tends to guess differently, depending on the nature of the errors(s). Different browsers may thus create radically different renderings of the page, with no guarantee that any of these renderings will match the author’s intention.

Web pages created with code that conforms to the relevant standards are most likely to display as the author intended.

Please Explain these W3C Buttons

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The W3C HTML 4.01 Button:    or 

Provides a link to an on-line validator for pages composed using HTML (HyperText Markup Language) version 4.01, which is the current standard. If you press this button, you will be presented with a form into which you can type (or copy and paste) the URL (Uniform Resource Locator) for a web page.

For instance, the link for this page is: picoparsec.org/pps-refs/w3c-buttons.html.

After you have typed (or pasted) a URL into the form, press the Check button.

The results will be displayed in green if everything on the page is valid.
If all is not perfect, warnings and errors will be displayed in orange and red.

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The W3C CSS Button:    or 

Provides a link to an on-line validator for pages composed using CSS (Cascading Style Sheets) Level 3, which is the current standard. If you press this button, you will be presented with a form into which you can type (or copy and paste) the URL (Uniform Resource Locator) for the style sheet associated with a set of pages.

In the worlds of PicoParsec and the Starving Artist’s Garratt,
the following cascading style sheets are used:

• picoparsec.org/websupp/css/pps-azure.css
• picoparsec.org/tsag/websupp/css/tsag-base.css
• picoparsec.org/tsag/websupp/css/tsag-azure.css
• picoparsec.org/tsag/websupp/css/tsag-oldbase.css
• picoparsec.com/websupp/css/tsagps-base.css

After you have typed (or pasted) a URL into the form, press the Check button.

The results will be displayed in green if everything on the page is valid.
If all is not perfect, warnings and errors will be displayed in orange and red.