It is becoming increasingly difficult for users to find the information they need with only traditional search technologies. While the amount of data on the internet expands exponentially (the major search engines now have indices that contain tens of billions of items), the amount of information entered for the average query (two to three words) has remained relatively steady. Mapping three words to billions of items is a profoundly difficult, if not mathematically impossible, task.
It is for this reason that we see statistics like these:
"People search for 11 minutes on average before finding what they're looking for, and half abandon searches without getting that far." - Microsoft
"Half of potential Web sales are lost because visitors simply can't find what they want." - Gartner
"According to Outsell, in a study indicating rising frustration with internet search, 'in many instances the culprit is search failure due to irrelevant results.'" - MediaPost, "Irrelevant Results Threaten Search"
"79% of professionals feel that their queries are not always understood and only 10% find what they are looking for on the first attempt." - Convera
Something more is needed.