Google believes it can make more money by placing some of its ads below its search results instead of alongside them.
The reshuffling began appearing on Google's website Wednesday.
The shift won't preclude ads from still appearing in the right column next to the search results.
Google found that certain ads generate more clicks when they appear at the bottom of the page. That's important to Google because it gets paid a certain amount each time an advertising link gets clicked. The company didn't specify what kinds of ads are likely to get the bottom-page billing.
Google Inc., which is based in Mountain View, Calif., regularly tweaks its search formula and advertising system in an effort to deliver better results to Web surfers and companies trying to promote their products.
The company's tactics have proven highly effective so far. Google handles about two out of every three Internet search requests. It is expected to sell more than $35 billion in advertising this year.