When you hear or read about the hidden or deep web, it’s anything behind a paywall, something with a password, or dynamically generated content on the fly and didn’t have a permanent URL. These are the things you are not going to find with a traditional Google search. So, where can you look? Thankfully, there are deep web search engines available on the web.Of course, there is a component of the Internet that is used for bad or illegal purposes, but a good analogy is that the Internet is like a huge city. You can find a lot of things that are helpful in a huge city, but there are likely dangerous places that you would be better off not visiting. How do you find what you want while avoiding the "bad" sections of town? The main way is to stay on clear and public areas rather than blindly "surfing" the web. If you look for evil things you will find them, so don't look.
For genealogists, one example of searching the deep web is looking for records in libraries and university special collections. Very few of these cataloged items will show up in a general Google search. The most obvious search engine for locating research materials in libraries around the world is WorldCat.org. As genealogists or family historians, we should be familiar with libraries and archives. But as I have seen recently here in Maryland while working at the Maryland State Archives digitizing records, the libraries and archives may still be working with their data a little bit back in the past. Here is a sight I saw during a recent visit to the Library of Congress.
I also see a huge card catalog every day at the Maryland State Archives. No Google search is going to help you find your records if they are still cataloged on a 3 x 5 card. When I write about all the records that are available online, there is always a caveat. There are many records that will not show up in a Google search and there are many others that are not yet discoverable by searching on the Internet.
What all this really boils down to is that research is open-ended. You really never get to the end of the possibilities. I have been searching for my Tanner ancestors in Rhode Island for years and yet I still haven't taken the time to go visit the libraries and archives in Rhode Island so I am undoubtedly missing something. Until I actually spend the time to visit those local libraries and archives, I will likely be missing something. But on the other hand, to make a cursory search of the Internet resources and think you have found everything online is delusional.
Now, I found that there is a book about my Tanner family and the only copy I know about is in a library in Florida. Is it worth the trip?