Until now, Google Adwords has offered two types of ad rotation: alternating or optimized depending on the click rate. Following discussions with advertisers, the engine decided to add a third rotation system: optimized according to conversions. So you now have the option of promoting the display of the ads that generate the most sales on your site …
Google is therefore continuing its momentum in integrating bidmanagement tools into its sponsored links platform. After optimizing bids based on predefined rules, the engine proposes to optimize the ads in the same way.
One of the techniques for optimizing Adwords campaigns is to create several ads in order to see the impact on click and transformation rates and then select the best performing ones.
With this evolution, Google will do some of the work for you. To activate this option, simply go to “campaign settings” then in “advanced settings” and check “Optimize for conversions”.
Note that to use this new bidmanagement service, you must have activated Google Adwords conversion tracking.
Source: Google Inside Adwords