Yes, Pay Per Click. The ads in the upper right hand corner are PPC ads on the Google Content Network for instance.
Someone clicks your ad on your site, you get money simple as that. Search google adsense on google to get started
PPC advertising is an inexpensive form of marketing which targets people who are already searching for your products or services. It is the placement of adverts on the search results page of Google, which are displayed when users search using keywords relevant to your industry. At its most basic level you are not charged anything for your ads to be displayed. It is not until somebody actually clicks on your ad and is directed to your website that you pay a small fee to Google, hence the term ‘pay per click’. Prices per click range from just 0.04p to a few pounds depending on the popularity of the search term. Naturally advertisers who pay more appear higher on the search results page. Google being the most widely used search engine commands the use of more than 85% of internet users worldwide.
Pay Per Click is exactly what it says. You Pay Per Click. If someone clicks you pay. Googleads is the most popular PPC model, but there are 1000's out there.