dir command

Here is a code snippet that I got from the php manual (php.net). I am confused about the "read" part of the command, mainly the "->" part. What does this mean? What is the handle? Is it necessary? I want to list only *.html files. How can I do that? What arguments go in the () in the read? As you can see I am a newbie. I did do a search, but I couldn't find any more specifics. <? $d = dir("."); echo "Handle: ".$d->handle."<br>\n"; echo "Path: ".$d->path."<br>\n"; while($entry=$d->read()) { echo $entry."<br>\n"; } $d->close(); ?>