The size of the World Wide Web

size_world_wide_web

The Indexed Web contains at least 4.73 billion pages (Friday, 13 November, 2015).

How is the size of the World Wide Web (The Internet) estimated?

The estimated minimal size of the indexed World Wide Web is based on the estimations of the numbers of pages indexed by Google, Bing, Yahoo Search. From the sum of these estimations, an estimated overlap between these search engines is subtracted. The overlap is an overestimation; hence, the total estimated size of the indexed World Wide Web is an underestimation.
Since the overlap is subtracted in sequence, starting from one of the four search engines, several orderings (and total estimations) are possible. We present two total estimates, one starting with Bing (BG) and one starting with Google (GB). The figure reported at the top of the page refers to the GB estimation.

The size of the index of a search engine is estimated on the basis of a method that combines word frequencies obtained in a large offline text collection (corpus), and search counts returned by the engines. Each day 50 words are sent to all four search engines. The number of webpages found for these words are recorded; with their relative frequencies in the background corpus, multiple extrapolated estimations are made of the size of the engine’s index, which are subsequently averaged. The 50 words have been selected evenly across logarithmic frequency intervals (see Zipf’s Law). The background corpus contains more than 1 million webpages from DMOZ, and can be considered a representative sample of the World Wide Web.

When you know, for example, that the word ‘the’ is present in 67,61% of all documents within the corpus, you can extrapolate the total size of the engine’s index by the document count it reports for ‘the’. If Google says that it found ‘the’ in 14.100.000.000 webpages, an estimated size of the Google’s total index would be 23.633.010.000.

The overlap between the indices of two search engines is estimated by daily overlap counts of URLs returned in the top-10 by the engines that were returned in a sufficiently large number of random word queries. The words were randomly drawn from the DMOZ background corpus.

(from http://www.worldwidewebsize.com)

 


 

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