From http://www.w3schools.com (Copyright Refsnes Data)

Introduction to HTML

HTML Example

<h1>My First Heading</h1>

<p>My first paragraph.</p>

</body>
</html>

Try it yourself

What is HTML?

HTML is a language for describing web pages.

HTML stands for Hyper Text Markup Language
HTML is not a programming language, it is a markup language
A markup language is a set of markup tags
HTML uses markup tags to describe web pages

HTML Tags

HTML markup tags are usually called HTML tags

HTML tags are keywords surrounded by angle brackets like <html>
HTML tags normally come in pairs like <b> and </b>
The first tag in a pair is the start tag, the second tag is the end tag
Start and end tags are also called opening tags and closing tags.

HTML Documents - Web Pages

HTML documents describe web pages
HTML documents contain HTML tags and plain text
HTML documents are also called web pages

The purpose of a web browsers (like Internet Explorer) is to read HTML documents and display them as web pages. The browser does not display the HTML tags, but uses the tags to interpret the content of the page:

<html>

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

</html>

Try it yourself

Example Explained

The text between <html> and </html> describes the web page
The text between <body> and </body> is the visible page content
The text between <h1> and </h1> is displayed as a heading
The text between <p> and </p> is displayed as a paragraph