How many sites are there on the Internet?
roughly 8 billion, that's 1.2 sites per person.
The Internet works like this-- * An HTML designer creates the websites * Then, he signs up with an ISP (Internet Service Provider) * There are many different ISP's, and they all host different people's sites. So, ISP's, AKA Webmasters, serve the sites on the Internet and designers create and manage the sites.
Since the launch of first social networking site, many such applications and sites took place on Internet. Some succeed to top the social networking world, which are known to us as Facebook, Orkut and Myspace. In current position, there are literally thousands of social networking sites available on Internet.
It is impossible to have a list of internet sites as there are constantly more websites being added and the Internet is every expanding. Just in the time answering this question alone, any 'list' would have been greatly altered by the changing internet sites, not to mention those sites who change names or relaunch.