The Four Statuses

1. 1Scheduled — the campaign's Start Date hasn't arrived yet. It will move to Running automatically once it does.
2. 2Running — the campaign is live and eligible to serve. (Running does not always mean spending — see Why Isn't My Campaign Spending? if a Running campaign shows $0 cost.)
3. 3Expired — the campaign's End Date has passed. It will not serve again unless you edit the dates or copy it into a new campaign.
4. 4Paused — the campaign has been manually paused and will not serve until resumed.

Important Notes

Approval is effectively immediate on Topple — there's no separate review status to wait through. If your creative doesn't meet spec, it simply won't serve; check Ad Specifications and Why Isn't My Creative Serving? rather than looking for a rejection notice.