A campaign is a series of operations designed to reach a goal.
Campaigns are marketing workflow that search to engage with the user
See Marketing - Automation (Campaign Automation)
If you:
all promoting the same product … you are witnessing a marketing campaign.
DSP execute campaigns.
After processing of an Activity Feed (Data from Purchase, Navigation, …)
via What are the UTM (Urchin Tracking Module) known as Campaign Parameters?