Saturday, August 11, 2012

HTML: Elements

HTML documents are defined by HTML elements.


HTML Elements
An HTML element is everything from the start tag to the end tag:

Start tag *
Element content
End tag *
<p>
This is a paragraph
</p>
<a href="default.htm">
This is a link
</a>
<br />



The start tag is often called the opening tag. The end tag is often called the closing tag.


HTML Element Syntax
  • An HTML element starts with a start tag / opening tag
  • An HTML element ends with an end tag / closing tag
  • The element content is everything between the start and the end tag
  • Some HTML elements have empty content
  • Empty elements are closed in the start tag
  • Most HTML elements can have attributes
Tip: You will learn about attributes in the next chapter of this tutorial.


Nested HTML Elements
Most HTML elements can be nested (can contain other HTML elements).
HTML documents consist of nested HTML elements.


HTML Document Example
<!DOCTYPE html>
<html>

<body>
<p>This is my first paragraph.</p>
</body>

</html>
The example above contains 3 HTML elements.


HTML Example Explained
The <p> element:
<p>This is my first paragraph.</p>

The <p> element defines a paragraph in the HTML document.
The element has a start tag <p> and an end tag </p>.
The element content is: This is my first paragraph.

The <body> element:
<body>
<p>This is my first paragraph.</p>
</body>

The <body> element defines the body of the HTML document.
The element has a start tag <body> and an end tag </body>.
The element content is another HTML element (a p element).
The <html> element:
<html>
<body>
<p>This is my first paragraph.</p>
</body>

</html>
The <html> element defines the whole HTML document.
The element has a start tag <html> and an end tag </html>.
The element content is another HTML element (the body element).




Don't Forget the End Tag
Some HTML elements might display correctly even if you forget the end tag:

<p>This is a paragraph
<p>This is a paragraph

The example above works in most browsers, because the closing tag is considered optional.
Never rely on this. Many HTML elements will produce unexpected results and/or errors if you forget the end tag .

Empty HTML Elements
HTML elements with no content are called empty elements.
<br> is an empty element without a closing tag (the <br> tag defines a line break).
Tip: In XHTML, all elements must be closed. Adding a slash inside the start tag, like <br />, is the proper way of closing empty elements in XHTML (and XML).



HTML Tip: Use Lowercase Tags
HTML tags are not case sensitive: <P> means the same as <p>. Many web sites use uppercase HTML tags.

I am using lowercase tags because the World Wide Web Consortium recommends lowercase in HTML 4, and demands lowercase tags in XHTML.

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