PPC is dominated by Google’s “AdWords,” Yahoo’s “Sponsored Search” and a few other feeder mechanisms. Advertisers bid on placements, which can vary widely, depending on reach and other factors. Sites serving as hosts for these ads receive a small remuneration every time one of their visitors clicks through to view the site behind an ad..
If a search engine algorithm senses a mismatch, it regards that as deception and penalizes the site, to preserve its own reputation. Naturally, the ad must be immediately compelling, if readers who fit your target demographics* are going to be compelled to click through from the content that originally they had navigated to see. It really has to be bang-bang compelling, and Tech Ninja Marketing will make sure it is.
* Cookies track their online activity, particularly regarding commercial sites, rendering a profile.