Like others have said, when you type something in the address bar it performs Google's "I'm Feeling Lucky" search, taking you to the first page in its rankings.
I'd suggest you change it:
Type
about:config in the address bar.
Type
browser.search.defaulturl into the Filter field.
Right click the URL under Value and click Modify
Paste one of the following URLs into the box
(Right click on the link, copy link location, then paste into the box)
Google.com search
Amazon.com search
Wikipedia search
Now when you type something in the address bar, it will search Google/Amazon/Wikipedia for what you typed. Saves you having to go to the site and then search. Only problem is, you can't use fullstops or colons.
Finally, this should be in Tech Talk.