In the year 2010 alone, Google had a mind boggling 29 billion in revenues. This amount of annual revenue is hard to comprehend. In the year 2010, 97 percent of Google’s revenue came from advertising, and this is possible because they received more than one billion visitors to their site each month. These are unique visitors. They are only counted once regardless of repeat visits to the search engine website.
Each visitor to Google is averaging 200 minutes of their time each month on the Google web page. This is more than a website, but has clearly become a part of our society. Businesses that want to be seen, advertise with Google. The leading areas of Adword revenue for Google are companies engaged in insurance, law, credit, mortgages and loans.
However, the fastest growing area of advertising revenue has been with mobile advertisements. The figure was 2.5 billion in 2010 and this figure is expected to be twice that in 2011.
From: http://www.businessmba.org