</4>

these are heading tag in HTML.
H1 is the largest in font size and H6 is the smallest in size in heading tag.
you have to add your contain in between tags.just like
<.h1>

Dont use the dot

<./h1>

<.h2>

Dont use the dot

<./h2>

<.h3>

Dont use the dot

<./h3>

<.h4>

Dont use the dot

<./h4>

<.h5>

Dont use the dot

<./h5>

<.h6>

Dont use the dot

<./h6>

you can do style by adding css....

<h1. style="color:blue;text-align:center;"> Dont use the dot </h1.>

you can resizing font by adding css....
<.h1>

dont use the dot

<./h1>