First of all, what is HTML validation?

HTML validation is the practice of comparing a site’s code to web standards. This, often overlooked, practice helps to identify errors and sub-standard code. The average user will not validate pages as they are browsing the internet and will most likely have no idea that they are viewing a page that is not standards compliant. Those who do validate and understand the process, however, use the results as a quality check.

Why would you want your site to be standards compliant?


In past experience, validating my code has helped me unintentionally discover programming and scripting errors that have caused the look and functionality of the site to be compromised. It can uncover issues like unclosed tags, obsolete markup, and elements that are nested improperly. Each browser will display the content a little differently in the first place, but these coding errors may also cause many other unexpected results when displaying the page for the user. When a browser recognizes invalid code, it is forced to guess how to display it, likely causing structure and layout problems as well as slowed loading speeds.

Search Engine Crawling Errors

In order to properly optimize a site for search, a search engine needs to be able to parse the markup. Noncompliant code can put up several roadblocks for search engines and, as mentioned before, the browsers themselves. When the closing tag of an element is forgotten, the browser must guess where to close it, and could easily cause problems with semantics. Search engines are similar in that most are built to handle a significant amount of errors but it is very hard to say which errors they can handle. The bottom line is that invalid code could cause the search engine to misunderstand your code and miss your most important content altogether.

Professionalism & Good Practices

As I mentioned before, most users do not validate the pages they come across because they most likely do not know how to, nor do they care. Honestly, I think it is safe to say that many people in the design/development world don’t even care as long as their site displays and functions the way they want it to. I may be different as things like that really bug me. I prefer to make sure that the pages I create pass all validation requirements for peace of mind and overall professional standards. In this day of continuous technological evolution, it is beneficial to always use best practices in order to make things easier to edit in the future.

Who validates?

For the purpose of this article, I checked the homepages of 8 of the most popular sites on the web for standards compliance. Here are the results:

  • Facebook – Fail – 36 errors
  • Google – Fail – 23 errors
  • Yahoo – Fail – Recieved Message: Sorry! This document cannot be checked
  • YouTube – Fail – 59 errors
  • Wikipedia – Pass
  • Amazon – Epic Fail – 423 errors
  • Craigslist – Pass
  • – Fail – 11 errors