A prospect can be in or out of campaign.
When prospects are in the campaign and the campaign is running it means they are receiving the steps of this campaign.
Out of campaign
When a prospect is out of a campaign it means he was previously in that campaign but he's not in anymore. A prospect can be out of a campaign for 4 different reasons:
Prospects for whom the campaign was stopped because they performed an action that triggered an exit.
Example are: they replied, clicked a link, have been qualified or have been converted.
Prospects who went through all the steps of the campaign and did not trigger an exit event. They basically received all the steps of the campaign and nothing happened.
Prospects for whom the campaign was stopped manually. The prospect has been manually removed from the campaign by a user of your account.
The prospect's email bounced. When that happens our system will automatically remove the prospect from the campaign.