required.html

<!--  Sending data is not enough — we also need to make sure that the data users fill out in forms is in the correct format that we need to process it successfully, and that it won't break our applications. We also want to help our users to fill out our forms correctly and not get frustrated when trying to use our apps. Form validation helps us achieve these goals

-->

<form action="/action_page.php">
  Username: <input type="text" name="usrname" required>
  <input type="submit">
</form>