Lesson 11

Why HTML/XHTML Verification is Required?

There are various reasons to verify your web page before hosting it over the internet.

• Any web page quality depends on how well you have written your web page.It should be syntactically correct and should pass all the Quality Gates.
• When any Search Engine does indexing for your web page content it might get confused if your HTML tags are not written properly and much of the web page content might not be indexed properly.
• There might be many HTML tags which you are using in your web page but then have been depreciated and many of the search engines also don't support them.
• Consistency, HTML Code Beauty, Process Compliance are always appreciated by good Webmasters.

What Is W3C Compliance?

The W3C is the World Wide Web Consortium and since 1994 the W3C has provided the guidelines by which websites and web pages should be structured and created. Here are the links to validate your web pages:

• Validate HTML/XHTML File against W3C Standard HTML/XHTML Validator.
• Validate CSS File against W3C Standard CSS Validator.

While doing verification you will get errors along with appropriate reasons. All the validations will be done using XHTML DTD which is a refined version of HTML.

Rules for W3C Compliance:

There are following rules which you should keep in your mind while writing your web pages.

• Use the XHTML declaration statements to start every XHTML page:
  

  "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd">

• Every tag must be closed.
• The head and body tags are now mandatory.
• Empty tags get a terminating slash. An empty tag is a tag that doesn't require an end tag. Examples include
  and

  ---

  .
  

  
   is now 
   />.
  
   is now 
  
   />. SRC="--"> is now  src="--" />

• All tags must be lower case. This does not apply to attributes, only tags. For example, both of these formats are acceptable under the XHTML DTD:
  

   color="#ffffcc"> is invalid color="#ffffcc"> is valid color="#FFFFCC"> is also valid

• All the attribute values should be put with-in double quote.
• Tags may not nested
  

  Text

This is invalidText This is valid

The

 tag should not contain: img, object, big, small, sub, or sup.

One

tag can not be inside another tag.

If your code contains a &, it must be written as &.

Any use of CSS should use all lower case lettering.