Google features two main advertising streams, Google Adwords and Google Adsense.
Adwords allow you to purchase advertising space on Google search result pages for your business, product or idea. You pay a set amount up front and Google matches your adverts with its search results.

The other stream is Adsense which is used by websites. this allows a site, however small, to generate income when a user see a link that interests them and they follow that advertising link by clicking on it.
This page has Google Adsense advertising on it at the top and the bottom of the page. If you are thinking of setting up a website, its a great addition to your plans to include Google Adsense.