draw a grey line in html code example

Example 1: horizontal line html

<!-- code -->

<hr>

<!-- code -->

Example 2: which is right or in html

<hr> <!--   it represents a horizontal line break, in HTML4.0 we use <hr>, 
            in XHTML1.0 we use <hr/>,  in HTML5(which is the current version of 
            HTML) we can use both <hr> and <hr/>    
       -->