Is it valid to put h3 (or any heading) inside td tags?

Question

The question is asked for TH tags, but I couldn't find one for TD tags.

Can I put headings inside <td> tags?

Answer 1

thead is not h3, if you use h3 inside td element, it is absolutely fine, but if you use h3 as a direct child to tr is invalid.

Inorder to use thead you can use it like this

<table>
   <thead>
      <tr>
         <th>This is table head and not h3</th>
      </tr>
   </thead>
   <tfoot>
      <tr>
         <td>Foot Cell</td>
      </tr>
   </tfoot>
   <tbody>
       <tr>
          <td>
             <h3>It's completely valid to put your h3 here</h3>
             Table cell
             <p>You can also use p tag here
           </td>
       </tr>
   </tbody>
</table>

But if you do it something like this, is invalid

<table>
   <tr>
      <h3>It's invalid</h3>
      <td>This is a cell</td>
   </tr>
</table>

You can always check here whether your markup is valid or not.