Why users scan

3. is this the right page?

Each page has to compete with hundreds of millions of other pages for the user's attention. Users don't know whether this page is the one they need or
whether some other page would be better: they are not willing to commit the investment of reading the page in the hope that it will be good. Most pages are in fact not worth the users' time, so experience encourages them to rely on information foraging. Instead of spending a lot of time on a single page, users move between many pages and try to pick the most tasty segments of each.

Source: Alertbox, http://www.useit.com/alertbox/whyscanning.html