CPC (Cost Per Click) — you pay each time someone clicks your ad. Good for driving traffic.
CPM (Cost Per 1,000 Impressions) — you pay for visibility, regardless of clicks. Good for brand awareness.
CPA (Cost Per Acquisition) — you set a target cost per conversion, and Kointent optimizes delivery toward that goal. Good once you have conversion tracking set up.
Most advertisers start with CPC or CPM, then move to CPA optimization once they have enough data.