Line Item: This object tracks all revenue in the system and defines how inventory will be purchased, including bidding strategies and media cost budgeting.
Creative: The actual advertisement to be served. The specification of a creative includes format, size and audit attributes.
Segment: Used for targeting specific groups of users who have been added to the segment through a pixel.
Conversion Pixel: These objects are used for tracking conversions as well as optimization for CPA campaigns and line items.
Profile: This object defines all of the targeting parameters for another object (e.g., line item). Please note that a profile is the only object that does not correspond to the objects in the UI. For example the UI combines a profile (targeting) and a campaign (budget and flight dates) and shows a campaign alone.