Explaining PPC ads
PPC advertising is a commonly used management method by many search engine marketing companies to drive traffic to a website. Advertisers literally pay-per-click, paying their host (for example, Google or adWords) only when their ad is clicked.
Google PPC
Google PPC ads will appear at the top of the Google search engine results page, or directly to the right, as ‘Sponsored links’, or, the ads will appear on websites and blogs by way of Adsense | Read more about Google Adwords

Bing PPC
Bing PPC ads will appear directly at the top of the Yahoo search engine results page, or directly to the right, as ‘Sponsored sites’.

Facebook PPC
The difference between Facebook PPC ads and other PPC ads is that Facebook is not a search engine, it is a Social Media site. Accordingly, PPC ad placement on Facebook differs from search engine PPC ad placements. Facebook PPC ads, or ‘Social ads’, appear either within a user's News Feed as sponsored content or in the ad space (the far right column of the site).