The cellspacing attribute on the table element is obsolete. Use CSS instead

This is a common error shown by validating HTML documents. This error comes when table cellspacing is used inside <table> tag as :

<!DOCTYPE HTML>
<html>
<head>
	<title>HTML Validation eroors</title>
</head>
<body>
<table cellspacing="10">
  <tr>
    <td>1</td>
    <td>2</td>
  </tr>
  <tr>
    <td>1</td>
    <td>2</td>
  </tr>
</table>
</body>
</html>

Replace cellspacing attribute with a CSS styles as :

<!DOCTYPE HTML>
<html>
<head>
	<title>HTML Validation errors</title>
</head>
<body>
<table style="border-spacing:10px;"> <!-- CSS -->
  <tr>
    <td>1</td>
    <td>2</td>
  </tr>
  <tr>
    <td>1</td>
    <td>2</td>
  </tr>
</table>
</body>
</html>