How to add a 'required' checkbox to a form

I have this on a contact form that (I believe) makes the email field mandatory, correct?

<td class="required_field">*</td>
<td>Email Address</td>
<td><input type="text" name="email" maxlength="40" style="width:400px; border: 1px solid #696969;" /><br /><br /></td>
</tr>
Can you please tell me how to make a checkbox required to be checked on the form?

 

Why you not use radio button?

 

After use that check box validation, you must validate it with PHP or other server side scripting...
Because if browser not support javascript that validate will not effect

 

Can you please tell me how to make a checkbox required to be checked on the form?

You can disable Submit button if checkbox is not checked.

<script type="text/javascript" src="http://code.jquery.com/jquery-1.10.2.min.js"></script>
<script> 
    $(function() {
    $('input.required').click(function() {
        var unchecked = $('input.required:not(:checked)').length;
        if (unchecked == 0) {
            $('#submitBtn').removeAttr('disabled');
        }
        else {
            $('#submitBtn').attr('disabled', 'disabled');
        }
        });
    });
</script>

<form method="post" action="submit.php">
<input type="checkbox" class="required" /> Click to check
<br />
<input disabled="disabled" type='submit' id="submitBtn" value="Submit">
</form>

Code (markup):

And don't forget to make a PHP test in submit.php, for users who disabled JavaScript.

Demo: http://www.mxscripts.com/test/checkbox_required.php

 

Thanks for that "disable Submit button if checkbox is not checked". That's great.
Can you provide some info on how to "make a PHP test in submit.php, for users who disabled JavaScript", please?

 

If I were you, I would search for tutorials and build it from scratch. That way you learn JS/PHP yourselve which improves your skills