</br> not working in firefox and chrome

You're looking for <br /> instead of </br>

Self closing tags such as br have the slash at the end of the tag.

Here are the other self-closing tags in XHTML:

• What are all the valid self-closing tags in XHTML (as implemented by the major browsers)?

If you are trying to put space between two divs and <br/> is not working then insert this code (between the divs) to get the <br/> tag working.

<div class="clear"></div>

and add

.clear {
    clear: both;
}

in your css file.

It should be <br> or <br /> not </br>