[fireknight]

I think it comes down to personal preference

Example in an echo statement with a single quotation you would use a double quotation in the tags.

echo'<td width="50%">TEST</td>';

Or the reverse

echo"<td width='50%'>TEST</td>";

Or the old way

echo'<td width=\'50%\'>TEST</td>';

echo"<td width=\"50%\">TEST</td>";

My preference would be

echo("<td width='50%'>TEST</td>");