Why <br /> element is an empty element and why it has no end tag?

Answer 1

@Andre: Not necessarily. The <p> and <li> need not be closed even though they contain content.

Answer 2

its purpose is to break a line. only elements that contain content need to be closed.

Answer 3

<br/> just BReaks 'one' line
It will work even if you don't close it...whereas "<br> </br>" in a HTML will break 2 lines.
If you don't close <b> tag, then your rest of the webpage will contain bold text, but that doesn't happen in case of <br> as it represents only 1 line break, not multiple line breaks!