PPC short for Pay Per Click, is one of the widely used models in search engine monetization. For example, Google and Bing offer PPC which enables businesses to bid for keywords and acquire first place in search engine results. PPC for some papular keywords such as web hosting, car rentals, etc costs several dollars per click

The page offers search engine dependency of various prominent search engines. Though the article is a bit older, the search engines are still inter related to one another one way other other. Prominent search engines includes Google, Bing, Yahoo, Ask, duckduckgo, and others.