How does Campaign Influence work and how do you configure it?

Campaign Influence is the feature that attributes Opportunity revenue to one or more Campaigns that touched the deal. Without it, you only know who the opportunity's "Primary Campaign Source" was; with it, you can attribute fractional or full credit to multiple campaigns based on customisable rules.

Two models:

• Campaign Influence 1.0 (the original) — automatic if you enable it. When a contact role is added to an opportunity, all of that contact's recent campaign memberships within a configured timeframe are auto-attributed. Limited to a single attribution model and primarily useful for the legacy "first touch" view.
• Customizable Campaign Influence (CCI) — modern. You define multiple attribution models (First Touch, Last Touch, Even, Custom), each with its own logic. Each opportunity gets a Campaign Influence record per (campaign, model) pair, with a percentage and currency value. Reports can then show pipeline by campaign by model.

Configuration:

1. Enable CCI in Setup.
2. Define your attribution models — Salesforce ships First Touch, Last Touch, Even; you can add custom ones via Apex (or via packaged solutions like Salesforce Marketing Cloud Account Engagement / Pardot).
3. Configure rules per model — e.g., First Touch grants 100% to the campaign of the contact's first campaign membership before the opportunity creation date.
4. Add the Campaign Influence related list to the Opportunity layout so users see attributions.
5. Build reports comparing models (Campaign Influence model report type).

Common use case: marketing wants to demonstrate ROI per campaign type. Without CCI, every deal gets exactly one attribution; with CCI, marketing can present "we touched this deal 4 times — Webinar, Email, Conference, Demo — under different models, here's the value claimed by each". CCI is essentially marketing-attribution analytics built into Salesforce.