Travel Comparison Sites

Question

It's just interesting how travel comparison sites work, and how to do it?

on travel comparison sites I mean sites that look for other websites to find various information about a particular flight and hotel, etc.

How can a website look for another site?

any information would be helpful.

thanks

Answer 1

Here are some APIs, see http://blog.programmableweb.com/2007/10/29/5-travel-apis-from-comparison-to-booking/