td meaning in css code example

Example: html td tag

<table>
  <tr>
    <th>Column 1 Heading</th>
    <th>Column 2 Heading</th>
  </tr>
  <tr>
    <td>Data in Column 1, Row 2</td>
    <td>Data in Column 2, Row 2</td>
  </tr>
  <tr>
    <td>Data in Column 1, Row 3</td>
    <td>Data in Column 2, Row 3</td>
  </tr>
  <tr>
    <td>Data in Column 1, Row 4</td>
    <td>Data in Column 2, Row 4</td>
  </tr>
</table>