Where we used header in html4?

Answer 1

The <header> element represents a container for introductory content or a set of navigational links.

A <header> element typically contains:

- one or more heading elements (<h1> - <h6>)
- logo or icon
- authorship information

You can have several <header> elements in one document.

 A <header> tag cannot be placed within a <footer>, <address>or another <header> element.
For Eg.
<article>
  <header>
    <h1>Most important heading here</h1>
</header>
</article>
source : null

Answer 2

@Shailendra
HTML course is available. Go and learn ;)

Answer 3

<div id="header">

Answer 4

brainstorming

Answer 5

y r u learning 4 when u have html5?