Google AdSense is a free program that enables website publishers of all sizes to display relevant Google ads and earn. Learn some Google AdSense secrets.
To avoid accidental clicks Google has made some changes in format of AdSense Ad Units now. Previously, visitors could click on the background and full text of an ad, but now they can click only on the title and URL of a text ad. No longer valid are clicks on the background and clicks on the text that is not the title or URL in the ad.
Many Bloggers and Webmasters rely on Google Adsense for advertisement and earnings. I recommend you read Quality Guidelines by Search Engines and admit the fact that Google can not be tricked and it is simply reasonable to be fair while writing and building quality content. If your behavior is not careful enough then read on and learn some lesson.