HTML Documents
An HTML element is defined by a start tag, some content, and an end tag:
<tagname>Content goes here...</tagname>
The HTML element is everything from the start tag to the end tag:
<h1>My First Heading</h1>
<p>My first paragraph.</p>
Nested HTML Elements
HTML elements can be nested (this means that elements can contain other elements).
All HTML documents consist of nested HTML elements.
The following example contains four HTML elements (<html>, <body>, <h1> and <p>):
EXAMPLE:
<!DOCTYPE html>
<html>
<body>
<h1>First Heading</h1>
<p>First paragraph.</p>
</body>
</html>
Example Explained
The <html> element is the root element and it defines the whole HTML document.
It has a start tag <html> and an end tag </html>.
Then, inside the <html> element there is a <body> element:
<body>
<h1>My First Heading</h1>
<p>My first paragraph.</p>
</body>
The <body> element defines the document's body.
It has a start tag <body> and an end tag </body>.
Then, inside the <body> element there is two other elements: <h1> and <p>:
<h1>My First Heading</h1>
<p>My first paragraph.</p>
The <h1> element defines a heading.
It has a start tag <h1> and an end tag </h1>:
<h1>My First Heading</h1>
The <p> element defines a paragraph.
It has a start tag <p> and an end tag </p>:
<p>My first paragraph.</p>
Never Skip the End Tag
Some HTML elements will display correctly, even if you forget the end tag:
<html>
<body>
<p>This is a paragraph
<p>This is a paragraph
</body>
</html>
Empty HTML Elements
HTML elements with no content are called empty elements.
The <br> tag defines a line break, and is an empty element without a closing tag:
EXAMPLE:
<p>This is a <br> paragraph with a line break.</p>
HTML is Not Case Sensitive
HTML tags are not case sensitive: <P> means the same as <p>.
The HTML standard does not require lowercase tags, but W3C recommends lowercase in HTML, and demands lowercase for stricter document types like XHTML.