What is <link rel="alternative" & <link rel="pingback

Hi,
i came across a website. and found this tags used. can somebody plese explain to me what are these??
<link rel=“alternate” type=“application/rss+xml” title=“RSS 2.0” href=“http://…/” />

<link rel=“alternate” type=“text/xml” title=“RSS .92” href=“http://…/” />
<link rel=“alternate” type=“application/atom+xml” title=“Atom 0.3” href=“http://…/” />
<link rel=“pingback” href=“http://…/xmlrpc.php” />

Please can you explain it to me, thanks

http://www.google.com/search?q=RSS
http://www.google.com/search?q=pingback

Will take a look, thanks

but, i tried this beofre and there are definitions. But, i am note sure where to use these.

Alternate is saying “If for some reason your RSS reader doesn’t support RSS2.0, you can use RSS0.92, or Atom0.3.”. It’s basically last-resort (alternate) feeds.

The pingback is how the “pingback” function of Wordpress works. If someone types the URL to your page and selects “Pingback all URL’s in this post” (in Wordpress), it’ll go to the URL, follow the pingback link, and post all of the required information to that page, which will then add a comment to the post specified.

Not really. “Alternate” means that the content of the page you’re on is available in another format. It doesn’t have to be for RSS feeds, and RSS 2.0 isn’t always the preferred flavor.

Here’s an example that provides a PDF of the page content as a print-media alternative to the webpage:


<link rel="alternate" type="application/pdf"
href="/content/about.pdf" media="print" />

Thanks.
ok i got the RSS part and alternate part, but i am still confused with the ping part. i looked at on http://www.hixie.ch/specs/pingback/pingback. and it explains completely how it works. BUT, as i am new in this, i am not getting the point.

help appreciated

The point of pingback is to automate reverse linking.