What is the Invisible Web and How to Use It?

Test Your Internet Knowledge

How much of the World Wide Web is Considered Hidden or Invisible (the Deep Web)?

  • 25-30%
  • 90-99%
  • 45-50%
See results without voting

by Vicki Parker

The Invisible Web, also called the Hidden Web or Deep Web, is that part of the Internet that is generally inaccessible to conventional search engines like Google or Bing. That means as an end user, you typically won't see it's content or even know it's there. When you receive "hits" from a search term or phrase, you are only seeing a fraction of what's on the Web because search engines only retrieve web pages. They miss material whereas subject directories may not. A good example is newspapers which publish online, but search engines can’t get past the registration barrier and therefore, the content does not appear when you browse. Database material is another example. Most search engines limit the number of pages they search, dumping older ones and adding new ones by preference (paid placement and paid inclusion).

There are also many private web and proprietary web sites which simply don’t get searched during the usual end-user search. This does not mean you need to opt out of using search engines, it simply means you need to learn how to use OTHER tools that will search the hidden web. In fact, the largest part of retrievable data on the Internet is hidden and it is estimated that the hidden web is at least 50 times larger than the crawled web. Considering an estimated 900 billion pages of information is stored on the Invisible Web, and just 25% of it has been indexed, there's a lot more than meets the eye.

Ways to Search the Invisible or Deep Web


There are several tactics you can utilize to find invisible web material. None of them, however, are fail-proof, and all of them may need to be used within a single search effort. Despite the Internet's ambiguity, here is a good place to start:

Pre-Emptive Searches

A pre-emptive search essentially means forming a strategy before you even get started. Lawyers frequently get preemptive strikes on jurors - why? Strategy. Likewise, you need a strategy to weed out unwanted content. When you're browsing the World Wide Web, think about what you are trying to accomplish first. For instance, if you are looking for database material, use boolean phrases that incorporate keywords such as database, repository and/or archive. Consider this example: enter "trains +database." Then enter "trains +archive." You get two totally different results of material not found on the everyday Internet. With the first search you will get the Amtrak Stations dbase. With the second search you will get a history of Amtrak. If you were to key in simply "trains," you would get Amtrak's Home Page and current schedule.

Additionally, you can narrow your scope by limiting searches to certain locales by using country extensions. A list of these can be found online by Googling "country codes for the internet." For example, to find out what the United Kingdom has to say about nuclear warfare, enter "nuclear warfare" Similarly, you can find what China has to say by entering "nuclear warfare," but bear in mind you may also learn what 'CNN' has to say about it.

Clearly, if you don't know these backdoor ways to unlock hidden data, you will never see it on your browser list. For more tips, read further.

Use File Extensions to Narrow Your Scope

If you use any type of office software, you are familiar with various file extensions like Microsoft Word -.doc; Word Perfect - .wpd; Excel - .xls, and so forth. These are important because you can isolate material by file extension on the web by prefacing your search with filetype: For instance, taking the example of trains a bit further, enter "filetype:mdb trains and you may get some fairly proprietary database information in most every language.

Just as you used the suffix .mdb to search for dbase files, you can use other file extensions to get stricter search results. Type in "filetype:ppt" with no space and your search term, and you will get nothing but Power Point files. Type "filetype:.pdf" and your search term and you will get Adobe Acrobat files only. The most common file type extensions are .doc (Word), .ppt (Power Point), .pdf (Adobe), .xls (Excel), and .jpg (Jpeg) or .tif (TIF) for images but any legitimate suffix can be used. Try this one: "filetype:ppt rainbows and you'll see some pretty sophisticated presentation about the physics behind a rainbow.


What is most often found on the Hidden or Invisible Web?

  • Pornography and Other "Dark" Things
  • Databases and Catalogs
  • Internal or Private Sites
See results without voting

Use Reverse Searching

Reverse searching means using reverse logic. Sometimes all you have are fragments of information. This information can lead you to the information you are really looking for. For example, key in a phone number and you may find several leads to who that phone number belongs to. Same principle works for physical addresses and email addresses. I've even used Google Earth to determine what type of vehicle someone drove. It doesn't always work, but it's a good place to start when you are clueless. There are a myriad of links and programs available to help you search backwards whether it's phone numbers, addresses, names or images.

Data Mining

Unfortunate for some, and most fortunate for others like marketing companies, the Web has done a great job of collecting information from various sources and making it publicly available. When you can extract and integrate this data from Web pages, you are data mining. Data mining is becoming more and more sophisticated and many tools have been developed allowing organizations to collect buyer patterns or preferences, demographic data, statistics, etc.

Data Mining is done through various types of data mining software or search engines. (formerly Teoma) has a built-in data-miner, so it is wise to use it when invisible material becomes important. For example, if you Google "crosswords," you will get free online crossword puzzles, the most popular puzzles such as USA Today and LA Times, but if you search for "crosswords" on, you will see a sidebar (to your right) of recent or relevant articles about crossword puzzles.

Another good search engine is WebCrawler. Search "frogs that bite" from your Google browser, and then try it from WebCrawler. You will see the difference is a fairly substantive one. WebCrawler will pick up several articles of good quality whereas Google will not unless you add the term article in your search. Students should use data mining when looking for research content.

Utilize an Invisible Web Pathfinder

The intent of a Pathfinder is to present a variety of resources on a particular topic. It operates outside the realm of paid placement and inclusion, so advertisements and popularity aren't necessarily controlling content. Pathfinders are also popular among students who often rely on topic searches that bear out the same results in every browser.

There are numerous invisible web pathfinders. Directories. search engines, and gateways such as Around the Web in 80 Days, A9, The Invisible Web Directory, and Pinakes are also good places to start. Gary Price and Chris Sherman have written an excellent book entitled "The Invisible Web: Uncovering Information Sources Search Engines Can't See" if you want to learn more.

Other Useful Tips

There are numerous other tips for searching the deep web. When you receive "Page Not Found" messages for invisible sites, delete all data following the question mark and run the search again. It may lead you to the homepage where you can then search for content again. This is important because webpages are constantly being updated and changed and links or urls become invalid in the process but the content may still be there.

Consider also that most search engines are designed to look for text, so pictures and graphics may get overlooked. If you are looking specifically for pictures or videos, use a search engine feature that targets them.

As you search the "deep" web, keep in mind that some of it is "dark." It has been dubbed the Dark Web because therein lines pornography, dating site content, black market opportunities, and so forth. The Dark Web has gotten so large that it is the topic of another article altogether, but the highly publicized Silk Road is just one good example.

Enjoy searching with your new techniques but be safe out there. Without a good firewall to protect you, you are subjecting yourself to viruses, hacking, and other dark things that lurk on the Web.

For more information on searching the invisible web, read these two links:;;

Schlein, Alan M. Find It Online: The Complete Guide to Online Research. Third Edition. 2003, Facts on Demand  Press, Tempe Arizona.

Http:// Information Literacy: Search Strategies and Information Literacy: Depth of Search.

Http:// Uncovering the Hidden Web,  Part I & II.

Comments 3 comments

alahiker28 profile image

alahiker28 5 years ago from the Deep South Author

Awesome, Onix1. Thanks for sharing.

Onix1 5 years ago

thanks for this!

i found a google deep / invisable web search engine

kowality profile image

kowality 6 years ago from Everywhere

This is amazing info,Alahiker. Stuff I absolutely had no idea about. I'll definitely bookmark this page. Thank You for this Hub.

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    Vicki Parker (alahiker28)226 Followers
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    Ms. Parker is a senior paralegal from Alabama. She earned her Bachelor's from Millsaps College in Mississippi. She freelances on the side.

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