What kinds of communication technologies are used by Amazon

I need to know what types of communication technologies are being used by Amazon.com, Barnes and Noble, and Books A Million for a school paper.

I know this post is fairly old, but for other people who are wondering...
Amazon uses their own communication technology, developed by their engineers. A lot of their technology was developed in PHP, CGI/PERL, HTML and Javascript.

Source: http://masteroftheweb.org