An HTML element usually consists of a start tag and end tag, with the content inserted in between:

<tagname>Content goes here...</tagname>

The HTML element is everything from the start tag to the end tag:

<p>My first paragraph.</p>
Start TagElement ContentEnd Tag
<h1>This is my first heading</h1>
<p>This is my first paragraph</p>
<br>  
HTML elements with no content are called empty elements. Empty elements do not have an end tag, such as the <br> element (which indicates a line break).

Example Explained

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

The <body> element defines the document body.
It has a start tag <body> and an end tag </body>.
The element content is two other HTML elements (<h1> and <p>).


The <h1> element defines a heading.
It has a start tag <h1> and an end tag </h1>.
The element content is: My First Heading.

The <p> element defines a paragraph.
It has a start tag <p> and an end tag </p>.
The element content is: My first paragraph.
<!DOCTYPE html>
<html>
<body>

<h1>My First Heading</h1>
<p>My first paragraph.</p>

</body>
</html>