human
technology, because other Web pages do not link to it, is called the
gpt
Deep Web. Such sites or pages can still be made publicly accessible without being made publicly indexable by, for example, using individual or mass emailings (also known as
human
) to distribute the URL to potential readers or customers, or by using types of Web links that cannot be found by spiders but can be seen and used by readers.
gpt
Spamming is a common method of distributing to potential customers links to sexually explicit content that is not indexable. Because the Web is decentralized, it is impossible to say exactly how large it is. A 2000 study estimated a total of 7.1 million unique Web sites, which at the Web's historical rate of growth, would have increased to 11 million unique sites as of September 2001. Estimates of the total number of Web pages vary, but a figure of 2 billion is a reasonable estimate of the number of Web pages that can be reached, in theory, by standard search engines. We need not make a specific finding as to a figure, for by any measure the Web is extremely vast, and it is constantly growing. The indexable Web is growing at a rate of approximately 1.5 million pages per day. The size of the un-indexable Web, or the
human
Deep Web,