php中tr标记是列还是行？

$userData = array(
    array("John", "Doe", "john.doe@example.com"),
    array("Jane", "Smith", "jane.smith@example.com"),
    array("Bob", "Johnson", "bob.johnson@example.com")
);

echo "<table>";
echo "<tr><th>First Name</th><th>Last Name</th><th>Email</th></tr>";
foreach ($userData as $user) {
    echo "<tr>";
    echo "<td>".$user[0]."</td>";
    echo "<td>".$user[1]."</td>";
    echo "<td>".$user[2]."</td>";
    echo "</tr>";
}
echo "</table>";