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>):
<!DOCTYPE html> <html> <body> <h1>My First Heading</h1> <p>My first paragraph.</p> </body> </html>
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 are two other elements: <h1> and <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:
<p>This is a <br> paragraph with a line break.</p>