For various reasons (e.g. script/dynamic/unlinked/limited-access/non-html content) the indexed web is only a portion of the world wide web and later studies want further claiming that the deep (un-indexed/unknown) web is ~500 times larger than the indexed web!
So… What is the size of the internet?
Well, how many pages are there?
According to boutell.com guesstimate we have ~ 29.7 billion indexed pages on the World Wide Web (updated to Feb. 2007)
http://worldwidewebsize.com suggest a ~22.34 billion indexed pages (Sep. 2007)
and I used a simple Google search for “or | -or +*” and got about 17,340,000,000 documents estimation from Google…
=> We are left out with nice round guesstimate average of 20 billion indexed pages.
= ~1300* Tera = ~1.3 Peta of known/indexed web which might hide a ~600 Peta of deeper web…