Campaigns belong to an advertiser, the goal of campaign is categorizing your ads based on a specific start date and end date, for example, if your advertiser has a special event and he wants to display specific ads only during the period of this event , or for example for x days before event starting, then the best way to manage is by setting up a specific campaign for these set of banners,
also, you can set a limit for the campaign, for example, you can limit the number of times to display campaigns for that banner daily, or stop displaying the campaign banners if the total number of clicks has exceeded x for example.
You can add an unlimited number of banners per campaign.
Campaign Create / Edit Screen.
Campaign View Screen