PHP operator confusion (a beginner's question) - php

Question

I'm trying to figure out someone else's code and have come across this piece of code:
$html = '<div class="event">' . "\n";
if (get ( 'Event_Image' ))
{
$html .= '<a href="' . get ( 'Event_Image' ) . '">'
. '<img src="' . pt () . '?src=' . get ( 'Event_Image' ) . '&w=100" alt="' . get_the_title () . '" />'
. '</a><br />' . "\n";
}
$html .= '<a href="' . get_permalink ( $eventId ) . '">' . // title="Permanent Link to ' . get_the_title_attribute() . '"
get_the_title () . '</a><br />' . "\n";
if (get ( 'Event_Time' ))
{
$html .= get ( 'Event_Time' ) . '<br />' . "\n";
}
if (get ( 'Store_Location' ))
{
$html .= get ( 'Store_Location' );
}
$html .= '</div><!-- event -->' . "\n";
$eventsArr [$dateArr] [$eventId] = $html;
}
My question: What does the .= mean? Does it add to the variable (in this case $html)?

Answer 1

Yes. See http://www.php.net/manual/en/language.operators.string.php.

Answer 2

It means concatenate/append the value on the right hand to the value stored in the variable:
$a = 'str';
$a .= 'ing';
echo $a; // string

Answer 3

Yes, you got it right, here is an example:
$str = 'Hello ';
$str .= 'World';
echo $str;
Result:
Hello World

Answer 4

It means concatinate equals. So
$var = 'foo';
$var .= 'bar';
echo $var;
// output is 'foobar'

Answer 5

It is concatenate, then assign.
Same as:
$html = $html . $someString;