Network relationship diagram
Below is a diagram outlining the relationships between some of the core API services for Ad Networks. You'll note that this mimics the User Interface setup with the exception of the profile object. On the back end, campaigns are created through a combination of a profile object, which includes targeting information, and a campaign object, which includes start and end dates, budget, and associated creatives.
Details for each of the API services displayed above can be found on their respective documentation UI pages: