Validating your Web page won't guarantee that it will appear just the way you want it.It only ensures that your code is free of syntax errors.When I make any changes to the script, I want to be sure I did not break anything.If your site has hundreds of pages, it is likely generated by a CMS such as Wordpress, Drupal or such.See https://github.com/validator/validator/releases/latest for the actual download file, and see https://validator.github.io/validator/ for more information Perhaps the most straightforward way to do this, is the way I do it all the time."View source" of the web page, select it all (ctrl a), choose "copy" (crtl c), tab over to the validator, and its "direct input" option, and paste it in (ctrl v). What if you have to validate a website with hundreds of pages? I run a website where most of the content is generated from Te X by a not-very-reliable Perl script.To solve this problem, the World Wide Web Consortium (W3C) – the non profit, standard setting consortium, responsible for standardizing HTML – created STYLES in addition to HTML 4.0.All major browsers support Cascading Style Sheets, although some, handle them slightly differently, which an be a pain to the website designer! External style sheets enable you to change the appearance and layout of all the pages in your Web, just by editing one single CSS document!
On the front page of the W3C’s Web site is a sidebar called W3 A to Z, which contains all sorts of links.These technologies, which we call "web standards," are carefully designed to deliver the greatest benefits to the greatest number of web users while ensuring the long-term viability of any document published on the Web.— Web Standards Group Even the most proficient Web designers sometimes fail to validate their documents — checking a Web document against the existing, DOCTYPE-specific technical specifications. HTML and CSS validation does not guarantee perfect Web documents, and some truly heinous Web sites can be designed that are completely valid.It’s basically like health code guidelines for a restaurant.A Web site needs to meet certain standards in order to be as least imperfect as possible.