The two biggest search networks are Google and Microsoft Bing (MSN). There used to be a third big search network, Yahoo, but in 2010, Yahoo and MSN combined their networks, and now, advertising through MSN is the same as advertising through Yahoo and vice versa.
According to Comscore, Google sites were responsible for 66.4% of the searches in the US in March 2012. MSN sites were responsible for 15.3%, and Yahoo sites were responsible for 13.7% of all searches. This means that 95.4% of all searches in the US in March 2012 occurred through one of three networks, and 2/3 of the searches occurred through Google.
As a result, when it comes to search marketing, Google is the biggest search network, and Google Adwords is the biggest place to advertise. Advertising through Google AdWords gives advertisers access to more than 2/3 of the searches that occur in the country in a given month. However, advertising on MSN’s network is also a choice many advertisers make. While MSN receives less traffic than Google, traffic on the MSN network often converts at a higher rate than traffic on Google’s network, and is also usually a little bit cheaper. As a result, many advertisers advertise on both networks.
The rules for ads on Google’s network are a little different than the rules on MSN’s network, though as Google continues to be the market leader, MSN’s rules have become similar to Google’s. Due to its market share, this blog will primarily focus on Google. Most of the information will apply to MSN too, however. We’ll do our best to point out where something is different across the engines, and please ask in the comments section if you have any questions on this point.