Google’s aim is to allow Adsense publishers to have as much control over the appearance of the ads as possible which is why they are highly customizable.

Along with the different format choices you also have control over the color of the different parts of the ad. Consequently you can adapt them to the color of your website making them appear less like ads and more like actual content.

The five parts of the ad which you can change the color on are:

1. The border color of the ad

2. The background color of the ad

3. The link color of the ad

4. The url color of the ad

5. The text color of the ad

To improve your click through rate read about Adsense Ad Color Optimization.