[PHP/MySQL] Looping through an array

Hello, I’m having trouble deciphering what is going on in the following code:

$query = "SELECT * FROM `tbl_users`";
$result = mysql_query($query) or die('Query failed: ' . mysql_error());

while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
    echo "	<tr>
    echo "<td>$line</td>";
    foreach ($line as $col_value) { // $line is an array
       echo "		<td>$col_value</td>
    echo "	</tr>

I know what the inner foreach() loop is doing but I don’t see how the while() loops works. How is “$line = mysql_fetch_array($result, MYSQL_ASSOC)” a condition? Wouldn’t it return the same value everytime if at all?

And another small question, when entering queries, is it necessary to suround the name of the table with the little tick marks (`) like in the first line? Or can I use single/double/no quotes?

Thanks a bunch. :azn: