Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<form action="demo_form.asp" method="post">
  <input type="text" name="fname" required>
  <input type="submit" value="Submit">
</form>

<p>If you click submit, without filling out the text field,
your browser will display an error message.</p>

</body>
</html>