The difference between <br> and <br/>

A lot of HTML references and programs are using <br/> instead of <br> lately, and I didn’t understand the difference between the two because they both do the same thing: forces a break in the current line of text. <br/> is XHTML compliant, which states that: Empty elements must either have an end tag or the start tag must end with />. For instance, <br/> or <hr></hr>. So what is