Writing Well-formed HTML

Writing HTML isn't difficult. One very important thing to remember when writing HTML: use the correct tag to mark up your code. For instance, if it's a paragraph, surround the text with paragraph tags. Don't just drop your text on the page and put two break elements after it.

Conformant HTML

The following tips will help you make sure that your HTML code conforms with recommendations.

  1. All elements (tags) and attribute names must be in lowercase.
    • <blockquote cite="http://www.americanrhetoric.com/speeches/Ihaveadream.htm"> <p>And so even though we face the difficulties of today and tomorrow, I still have a dream.</p> </blockquote>
    • The element is blockquote, with a start tag and an end tag in lowercase.
  2. All attributes names must have values, and those values must be quoted.
    • <a href="/xyz.html" title="Link to xyz document">
    • a is the element, with href and title attributes. All in lowercase and quoted.
  3. Close all tags.
    • Example: <li>some text here</li>
  4. "Empty" elements must end with />.
    • Example: <br/> or <hr/>.
    • Example: <img src="/flower.gif" alt="flower"/>
  5. Properly nest all of your code:
    • Example: <p><b>This is correct</b></p>
    • Example: <b><p>This is INCORRECT</b></p>
  6. No double dashes within a comment tag.
    • Example: <!-- This is correct - and proper -->
    • Example: <!-- This is INCORRECT -- and may cause problems-->
  7. Encode all ampersand (&) and less-than (<) signs with &#38; or &#60;. Code for other common HTML entities are easily found  Exit.
    • When using a character or numeric entity, be sure to end it with a semicolon.
  8. For links in the same page, use id, rather than name. There are times, such as this Drupal WebCMS WYSIWYG Editor, where you'll use name instead. Don't worry.
    • Link to another part of the page: <a href="#section2">Section 2</a>
    • Where the link should point: <h2 id="section2">Section 2</h2>
    • Note that you can use id within any element to uniquely identify it. Once an element has that unique identifier, you can point to it with an anchor link.
  9. Validate! Use the W3C validator  Exit. Validation is an excellent way to find errors in your markup.

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Guidance for Good Markup

To view the example usage for any item within this document, please view the source.

Header Examples

The main page title (heading) of this guide is a heading 1 (h1) element. Reserve h1 for individual page titles only.

The secondary header ("Header Examples") is an h2 element, which may be used for any form of important page-level header. More than one may be used per page. Consider using an h2 unless you need a header level of less importance, or as a sub-header to an existing h2 element. Any header level may include links.

Third-Level Header

The header above is an h3 element, which may be used for any form of page-level header which falls below the h2 header in a document hierarchy. More than one may be used per page.

Fourth-Level Header

For all headers below third-level, follow the guidelines listed above. Only use lower header levels when necessary. I tend to use h4 in place of <p><strong>Your text here</strong></p>.

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Link Examples

External and internal links are handled differently.

External links
Internal links
Code EPA internal links as usual. title attributes are not necessary, but helpful.
Example: <a href="http://www.epa.gov/internalURLhere/" />
Internal PDF links
Links to PDF documents. For more info, see EPA's PDF linking standard.
Anchor links
For links within pages, use id attributes, not name attributes (name is deprecated). It is understood that the Drupal WebCMS WYSIWYG Editor uses name.

As an example of an anchor link, consider the "jump lists" in the "table of contents" above. Each link in the box is written <a href="#linkexamples">Link Examples</a>. Clicking on "Link Examples" brings you to the Link Examples heading, which is coded as <h2 id="linkexamples">Link Examples</h2>.

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All paragraphs are wrapped in p tags. (If you have a quote, paragraphs can be wrapped within a blockquote element. EPA has a pull-quote standard, which can be use for the same purpose.)


Historically, blockquote has been used purely to force indents, but this can now be achieved using CSS. Reserve blockquote for quotes. Here's an example of correct usage:

Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Cras euismod fringilla arcu. Integer posuere. Aliquam ipsum. Donec eget massa ac orci tempus euismod. Donec quis neque nec neque consequat sollicitudin. Donec commodo tempor nulla. Suspendisse venenatis. Ut ut leo. Nunc placerat urna at libero. Nunc suscipit lacus.

lipsum.com Exit

Additionally, you might wish to cite the source, as in the above example. (The correct method involves the cite attribute directly applied to the blockquote element, but since no browser makes any use of that information whatsoever, it's useful to also specify the standalone cite element.)

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Inline Text

There are a number of inline HTML elements you may use anywhere within other elements, including abbr, acronym, cite, code, del, em, ins, kbd, strong, and var.


Used for any abbreviated text, whether it be acronym, initialism, or otherwise. Generally, it's less work and useful (enough) to mark up only the first occurrence of any particular abbreviation on a page, and ignore the rest. Any text in the title attribute will appear when the user's mouse hovers the abbreviation (although notably, this does not work in Internet Explorer). Example abbreviations and usage: NASA, HTML, and Mass.


Used for only specific abbreviations. Like abbr, any text in the title attribute will appear when the user's mouse hovers the acronym (unlike abbr, however, this does work in Internet Explorer. According to Mirriam Webster  Exit, acronyms are:

...a word (as NATO, radar [...] ) formed from the initial letter or letters of each of the successive parts or major parts of a compound term; also : an abbreviation (as FBI) formed from initial letters.

If you think the difference between acronym and abbr is esoteric, you're right.


Used for computer code samples. Useful for technology-oriented sites, not so useful otherwise. Example code and usage:

function getJello() {
  echo $bill_cosby_mugs;

Inline usage: just like elsewhere in this document, HTML elements like em or code can be considered code, and marked up as such.


Used for defining a citation or reference to other information sources. Example cited text and usage: More information can be found in [ISO-0000].


Used for deleted or retracted text which still must remain on the page for some reason. Since the default style includes a strikethrough line, it's preferable to the s element. The del element also has a datetime attribute which allows you to include a timestamp directly in the element. Example deleted text and usage: She bought two five pairs of shoes. (Write the datestamp as so: datetime="2012-09-12".)


Used for denoting emphasized text. In most instances where you'd want to italicize text (using the HTML element i or otherwise) you should use the em element instead. Notable exceptions are stylistic italicizing of proper titles, foreign languages, etc. where italicizing is used for differentiation instead of emphasis. In those cases, no proper HTML elements exist, so an i element or a span element with a custom class may be preferable. Example emphasized text and usage: You simply must try the negitoro maki!

Reserved for the "new!" javascript function.

Used for text which should be typed by the user. Mainly useful for computer instructions. Example keyboard text and usage: Please press Enter to continue.


Used for denoting stronger emphasis than the em element. In most instances where you'd want to bold text (using the HTML element b or otherwise) you should use the strong element instead. Notable exceptions are stylistic bolding of examples, first occurrences of names in an article, etc. where bolding is used for differentiation instead of emphasis. In those cases, no proper HTML elements exist, so b element or a span element with a custom class may be preferable. Example strong text and usage: Don't stick nails in the electrical outlet.


Used for variables within computer code snippets. Useful for technology-oriented sites, not so useful otherwise. Example code and usage: Add 5 to $result and recalculate.

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Then there are the lists. ul denotes an unordered list (ie. a list of loose items that don't require numbering, or a bulleted list). ol denotes an ordered list, and various numbering schemes are available through the CSS (including 1,2,3... a,b,c... i,ii,iii... and so on). Each item within the ul or ol requires a surrounding <li> and </li> tag, to denote individual items within the list (as you may have guessed, li stands for list item).

Example lists and usage:

  • This is an unordered list.
  • It has two items.
  1. This is an ordered list.
  2. It has two items.
  3. No, I lied, it has three.

The Area Navigation (sidebar), the breadcrumbs, and the global footer are marked up as a list of links. You can see that it is possible to style each list in alternative ways.

Lists within lists are written as follows:

  <li>List item
      <li>Sub-list item</li>

Additionally, dl is another list type called a definition list. Instead of list items, the content of a dl consists of dt (Definition Term) and dd (Definition description) pairs. Though it may be called a "definition list", dl can apply to other scenarios where a parent/child relationship is applicable. For example, it may be used for marking up dialogues, with each dt naming a speaker, and each dd containing his or her words.

This is a term.
This is the definition of that term, which both live in a dl.
Here is another term.
And it gets a definition too, which is this line.
Here is term that shares a definition with the term below.
Here is a defined term.
dt terms may stand on their own without an accompanying dd, but in that case they share descriptions with the next available dt. You may not have a dd without a parent dt.

Created by Dave Shea  Exit; adapted by Michael Hessling.

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