What does mean in web pages?

th defines the header cell in the table.

There are two types of cells in the html form:

1: Header cell - contains header information (created by th element)

2: Standard cell - contains data (created by td element)

Note: Text inside a th element is usually rendered as centered bold text, while text inside a td element is usually left-aligned normal text.

The following is an example:

<table border="1">
  <tr>
    <th>名字</th>
    <th>电话</th>
  </tr>
 
  <tr>
    <td>甲</td>
    <td>45212154561</td>
  </tr>
</table>

The final output result is as follows: