Search Engine limitations

Date: [7/25/2008] 
1 trillion (as in 1,000,000,000,000) unique URLs on the web.

March 1, 2013:  Google says that the web now has 30 trillion unique individual pages. 

The estimates vary from 15 to some 30 billion Web pages.
Additionally, the different search engine services have some overlap with each other, and there exist pages and Web sites not indexed by any of them. Some search engines are designed to build a database of specialized information, such as medical or legal Web sites and Web pages.
Search engines search databases that are filled with words and document addresses, but that doesn't mean they have the intelligence to know what those words mean or in what context they're used. Searching for documents that contain the word "theater" won't find documents containing any related words, such as "play." On the other hand, if you're searching for documents containing the word "play," your results could easily include documents that contain the word play in the context of a "sports play" or "games children play."

The high demand for search continues because people can now obtain in mere seconds information that 20 years ago would have required a trip to the library, the use of a card catalog and a physical search through halls of printed volumes, a process that could easily have consumed two hours or more. Through the new channel of search, people can conduct many of their shopping, banking, and social transactions online, something that has changed the way our global population lives and interacts. This dramatic shift in behavior represents what investors like to label a disruptive event, which is an event that has changed something in a fundamental way.
Search engines have been at the center of this disruptive event, and having a business's website content appear prominently in the search engines when people are looking for the service, product, or resource that business provides is critical to its survival. As is the case with most paths to success, obtaining such prime search result real estate is not a simple matter, but it is one that this book aims to deconstruct and demystify as we examine, explain, and explore the ever-changing art of search engine optimization (SEO).