<table> tag in HTML is used for rendering TABLES in the html web page. <th>, <tr> and <td> tags are used in conjunction with the <table> tag to draw  a table in HTML.

<th> tag is used for the header row. There can be only one occurence of header row in a table. Text within this tag is bolded.
<tr> tag signifies a row in table. A Table consists of multiple rows.
<td> tag signifies the data in table. All data/content comes inside the <td> tag. A Row contains of multiple <td> tags.

<table border="1">
<tr><th>Heading1</th><th>Heading2</th></tr>
<tr><td>Row1 Col1</td><td>Row1 Col2</td</tr>
<tr><td>Row2 Col1</td><td>Row2 Col2</td></tr>
</table>

The above code will display a table of 2X2 dimensions as shown below: