Mining the Deep Web: Search strategies that work

13.12.2006
Just because a Web search engine can't find something doesn't mean it isn't there. You may be looking for info in all the wrong places.

The Deep Web is a vast information repository not always indexed by automated search engines but readily accessible to enlightened individuals.

The Shallow Web, also known as the Surface Web or Static Web, is a collection of Web sites indexed by automated search engines. A search engine bot or Web crawler follows URL links, indexes the content and then relays the results back to search engine central for consolidation and user query. Ideally, the process eventually scours the entire Web, subject to vendor time and storage constraints.

The crux of the process lies in the indexing. A bot does not report what it can't index. This was a minor issue when the early Web consisted primarily of static generic HTML code, but contemporary Web sites now contain multimedia, scripts and other forms of dynamic content.

The Deep Web consists of Web pages that search engines cannot or will not index. The popular term "Invisible Web" is actually a misnomer, because the information is not invisible, it's just not bot indexed. Depending on whom you ask, the Deep Web is five to 500 times as vast as the Shallow Web, thus making it an immense and extraordinary online resource. Do the math: If major search engines together index only 20% of the Web, then they miss 80% of the content.

What makes it deep?