HTML documents are defined by 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>|
* The start tag is often called the opening tag. The end tag is often called the closing tag.
Tip: You will learn about attributes in the next chapter of this tutorial.
Most HTML elements can be nested (can contain other HTML elements).
HTML documents consist of nested HTML elements.
The example above contains 3 HTML elements.
The <p> element:
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:
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:
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).
Some HTML elements might display correctly even if you forget the end tag:
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 .
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 tags are not case sensitive: <P> means the same as <p>. Many web sites use uppercase HTML tags.
W3Schools use lowercase tags because the World Wide Web Consortium (W3C) recommends lowercase in HTML 4, and demands lowercase tags in XHTML.
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