<form action="demo_form.php" method="get">
Choose your favorite subject:
<button name="subject" type="submit" value="html">HTML</button>
<button name="subject" type="submit" value="css">CSS</button>
<button name="subject" type="submit" value="javascript">JavaScript</button>
<button name="subject" type="submit" value="jquery">jQuery</button>
</form>