Campaign, Ad Group, Ad

Pinterest campaigns run on three nested levels: the campaign sets the objective, the ad group sets audience and budget, and the ad is the individual promoted Pin.

You choose the objective once at the campaign level, and it locks the optimization and available bid types below it. Inside the campaign you build one or more ad groups, each carrying its own targeting, budget, schedule, and bid. Ads sit inside the ad group, and each ad points to a Pin. Splitting audiences means new ad groups, not new campaigns.

A skincare brand runs one Conversions campaign, then builds two ad groups: one targeting a retargeting audience of past site visitors, one targeting an interest audience around "clean beauty." Each group holds four product Pins, so the campaign carries eight ads total.

The objective is fixed after launch. You cannot switch a campaign from Awareness to Conversions later; you rebuild it. People waste learning data trying to repurpose the wrong campaign instead of starting the correct one.

Objective up top, audience in the middle, Pin at the bottom.