Google VP Marissa Mayer gave a speech in which she signaled the company's desire to move toward a cost-per-action model, reports CNET.

Different from traditional cost-per-click ads, where advertisers pay for every click, CPA ads only ring up charges when a specific task is accomplished. That could include filling out a lead form, reading a newsletter or anything else designated by the advertiser. CPA ads also have a subsequently higher cost since it's a higher hurdle the visitor must clear.

Mayer reiterated in her comments, made at the Search Engine Strategies conference, that a bonafide CPA model is years in the making. CPA ads will be harder for fraudsters to take advantage of since an actual action beyond a click is required.