Marketing
Sub-ID
Definition
A parameter added to an affiliate tracking link to identify the page, placement, campaign or creative that produced the click, so that conversions reported by the operator can be attributed below the level of the affiliate account. The tool that turns affiliate reporting into page-level performance data.
Key takeaways
- A sub-ID is a parameter on a tracking link identifying the page, placement or campaign that produced a click.
- It turns an affiliate’s total conversions into page-level performance data and drives EPC and placement decisions.
- Operators use it to spot anomalous traffic, such as registrations with no deposits from one source.
- Sub-IDs identify placements, not people; customer-level data is limited by data protection and the agreement.
Why it matters
An operator's affiliate report says how many customers an affiliate sent; the sub-ID says where they came from. An affiliate running three hundred pages, six newsletters and a video channel appends a sub-ID to every link (the page slug, the position on the page, the campaign name) and the operator passes it back in reporting and postbacks, so that each conversion can be traced to the placement that produced it. Without sub-IDs an affiliate knows its total; with them it knows that the comparison table on one page converts at three times the rate of the review on another, and it can rebuild the site around what works.
The mechanism is simple and its uses are wide. Sub-IDs separate the performance of pages, of positions on a page, of email versus web traffic, of paid campaigns from organic, and of sub-affiliates and creators from the affiliate's own properties. They feed the earnings-per-click calculations that decide which operator gets which placement, and the cohort analysis that tells an affiliate whether a page's customers are worth the revenue share they generate. Operators use them on their own side to detect anomalies, such as a sub-ID producing registrations with no deposits, which is the signature of incentivised or fraudulent traffic.
The limits are data protection and the operator's willingness. A sub-ID that identifies an individual, rather than a placement, is personal data; operators restrict what they pass back at customer level for that reason, and affiliate agreements specify what reporting includes. Most affiliate platforms support several sub-ID fields, and the affiliate's tracking discipline (consistent naming, a single source of truth for what each value means) is what makes the data usable.
Frequently asked questions
How many sub-IDs can a tracking link carry?
Most affiliate platforms support several fields, commonly two to five, so an affiliate can encode page, position and campaign separately. Naming conventions matter more than the number of fields.
Do sub-IDs appear in postbacks?
Usually yes. The operator passes the sub-ID values back with each conversion event, so the affiliate’s tracking system can attribute the registration or deposit to the placement that produced the click.
Is a sub-ID personal data?
Not if it identifies a placement or campaign. If an affiliate uses it to identify an individual reader, it becomes personal data and the data-protection rules on tracking apply.