What is Attribution?
When a user visits your site, they rarely come from a single source. They might discover your product through a Google Ad, leave, come back from an email campaign, and finally convert through a direct visit. Attribution is how you decide which of those touchpoints gets the credit for the conversion. The CMS script’scms_rf parameter-based cookie system is a lightweight, first-party implementation of this concept no third-party dependencies, no cross-domain complexity, just clean URL-parameter tracking stored directly in the browser.
The CMS script uses last-click attribution by default.
How the cms_rf Cookie System Works
On page load, the CMS script checks the URL for the cms_rf parameter. If present, it runs attribution logic that either sets the cookie for the first time or updates an existing value.
User arrives on site
The user clicks a link with
?cms_rf=google_cpc appended to the URL (e.g., from a paid ad, email, or affiliate link).Cookie logic runs
Based on the attribution model, the script either sets the cookie (if not set) or overwrites it (if already set).
The
cms_rf cookie is a first-party cookie, which means it lives in the user’s browser under your own domain. This makes it more reliable than third-party tracking pixels in an era of increasing browser privacy restrictions (Safari ITP, Firefox ETP, etc.).First-Click Attribution
In first-click, the first touchpoint that introduced the user is retained. Once thecms_rf cookie is set, it is not overwritten even if the user returns later with a different cms_rf value.
Example scenario
| Visit | URL Parameter | Cookie Value (First-Click) |
|---|---|---|
| 1st | cms_rf=google_cpc | google_cpc ✅ Set |
| 2nd | cms_rf=email_newsletter | google_cpc 🔒 Locked |
| 3rd | cms_rf=referral_partner | google_cpc 🔒 Locked |
When to use First-Click
- You want to understand what drives awareness and top-of-funnel traffic.
- You want credit to remain with the first recorded source across return visits.
- Your customer journey typically spans multiple sessions before conversion.
Last-Click Attribution
In last-click, the most recent touchpoint is retained. Every time a user arrives with a newcms_rf value, the cookie is overwritten. So the stored value reflects the last channel seen before converting.
Example scenario
| Visit | URL Parameter | Cookie Value (Last-Click) |
|---|---|---|
| 1st | cms_rf=google_cpc | google_cpc ✅ Set |
| 2nd | cms_rf=email_newsletter | email_newsletter 🔄 Updated |
| 3rd | cms_rf=referral_partner | referral_partner 🔄 Updated |
When to use Last-Click
- You want to know what closes deals and drives final conversions.
- You want the attribution value to reflect the most recent recorded source before conversion.
- Your customer journey is short and straightforward.
Which Model is Better?
There’s no universally “better” model. Each answers a different question.- First-Click
- Last-Click
- Your primary marketing goal is brand discovery and awareness
- You run significant spend on top-of-funnel channels (paid search, content, social) and need to justify ROI
- Your conversion cycle is 30+ days
- You’re trying to understand what channel to invest in to grow your audience
Summary
| Type | First-Click | Last-Click |
|---|---|---|
| Cookie set | Once only | Every new cms_rf |
| Cookie overwritten | Never | Always |
| Credits | Original source | Most recent source |
| Best signal | Awareness & discovery | Conversion & closing |
| Cookie expiry strategy | Longer (60–90 days) | Longer (60–90 days) |
| Complexity | Low | Low |