When a web browser displays a page such as the one you are reading now, it reads from a plain text file, and looks for special codes  "tags" that are marked by the < and > signs. The general format for a HTML tag is:

example:

     <h1>What are HTML tags?</h1>

This  <h1> tag tells a web browser to display the text What are HTML tags? in the style of header level 1 (we will explain headers later). It is important to note that the there are two types of tags

    <tag name>  opening tag

    </tag name> closing tag

The "/" slash character tells a web browser to stop tagging the text. Most of  HTML tags are paired this way. If you forget the closing tag, a web browser will continue the tag for the rest of the text in your document, producing undesirable results.

Notes about tags

1-A web browser does not care if you use upper or lower case letters. For example, <h1>...</h1> is no different from <H1>...</H1>.

2-If you make a typographical mistake in your HTML code  your web page will simply look wrong. It is quick and easy to go inside the HTML document and correct the mistake.