Understanding the web user's psychology is a key aspect for the success or failure of an entire web site that hinges on a single concept or design. In all its forms, all the web architecture is based on the simple idea of search and find. This is something with a vast, metaphorical meaning that ranges over time, space and cultures. In an ancient, epic poem, the hero seek something to achieve an higher power or an intellectual revelation. As Vladimir Propp correctly pointed out in his seminal essay on fairy tales, searching is finding or, to a certain extent, it simply reveals the truly becoming of a man, his changing through the meaning of his whole existence that finally is clear and well-defined.
We're all searching for something, either in the real or in the web world. We're searching for something that satisfies our search criteria or, more broadly, the meaning of the search itself. It doesn't matter what we're searching for, but only the thing, the idea, the page, the file, the image that makes our research real. In the Silence of the lambs, the main character Hannibal Lecter says that what's important is what we seek. And we seek what we see every day.
For a site, it's not important to be high-ranked in search engine results. What is really important is satisfying the search criteria of our potential visitors. Further, it's important to have an efficient internal search system that allows our users to find what they're looking for. Even if you get an high page rank, you'll probably find out that you've very few visitors, at least when you compare the number of the actual visits to the number you originally wanted to get.
A user who finds something is more than a potential customer: he's almost a happy customer, just because he did find what he was searching for. Then all depends on your ability of turning a casual visitor into a devoted customer. Anyway, when a search ends, another one is just beginning. And on, and on, Since the very beginning of the web.