PHP operator confusion (a beginner's question)
<p>I'm trying to figure out someone else's code and have come across this piece of code: </p>

<pre><code>            $html = '&lt;div class="event"&gt;' . "\n";

        if (get ( 'Event_Image' ))
        {
        $html .= '&lt;a href="' . get ( 'Event_Image' ) . '"&gt;'
        . '&lt;img src="' . pt () . '?src=' . get ( 'Event_Image' ) . '&amp;amp;w=100" alt="' . get_the_title () . '" /&gt;'
        . '&lt;/a&gt;&lt;br /&gt;' . "\n";
        }

        $html .= '&lt;a href="' . get_permalink ( $eventId ) . '"&gt;' . //  title="Permanent Link to ' . get_the_title_attribute() . '"
get_the_title () . '&lt;/a&gt;&lt;br /&gt;' . "\n";

        if (get ( 'Event_Time' ))
        {
            $html .= get ( 'Event_Time' ) . '&lt;br /&gt;' . "\n";
        }

        if (get ( 'Store_Location' ))
        {
            $html .= get ( 'Store_Location' );
        }

        $html .= '&lt;/div&gt;&lt;!-- event --&gt;' . "\n";

        $eventsArr [$dateArr] [$eventId] = $html;
    }
</code></pre>

<p>My question: What does the <code>.=</code> mean? Does it add to the variable (in this case <code>$html</code>)? </p>
