Pay-per-click advertising

Which firm invented pay-per-click advertising? Why does Google dominate today and not this firm?
How are ads sold via Google search superior to conventional advertising media such as TV, radio, billboard, print, and yellow pages? Consider factors like the available inventory of space to run ads, the cost to run ads, the cost to acquire new advertisers, and the appeal among advertisers.
How do you, your friends, or your family members search on mobile devices? How has search changed over time? Are there certain product categories that you used to go to Google for, but where you’ll now rely on an app? How do you suppose this impacts Google’s revenue? If you were Google, how might you combat challenges as search shifts from a single search engine to niche apps?
Explain what AdSense is. On a percentage basis, how important is AdSense to Google’s revenues?
Imagine the two scenarios below. Decide which type of campaign would be best for each: text-based CPC advertising or image ads paid for on a CPM basis. Explain your reasoning.

Netflix is looking to attract new customers by driving traffic to its website and increasing online subscriptions.
A movie studio would like to promote the upcoming theatrical release of a new, major motion picture.