How do websites like www.meebo.com or www.e-messenger.net work? Do they use php to connect to the servers?

I'm interested in how they work, there alot of sites like this and since theres alot I was thinking that it might be easy to make such a site.

they use the xmlhttprequest object to transfer data to and from the clients browser , on the php side they must have some way to communicate with a main script which handles and the connections.
http://www.google.com/url?sa=t&ct=res&cd=1&url=http%3A//developer.apple.com/internet/webcontent/xmlhttpreq.html&ei=1oUXRIeEB6KOowLMsoTzAQ&sig2=INM5FyIJimZKZrtQ5pGZ6g

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Originally posted by Matty
They use php yes.

They are somewhat difficult to make if you don't know php or sockets.

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