Glossary

Sub ID (sub1–sub5)

A sub ID is a free-form label appended to a tracking link — most platforms accept several, typically sub1 through sub5 — used to segment traffic in reports. Media buyers put the placement, creative, keyword, or site ID into sub IDs so they can see which slice of traffic converts and cut the rest.

Sub ID vs click ID

A click ID is unique per click and exists for attribution; a sub ID is a reusable label shared by many clicks and exists for analytics. A campaign might have thousands of clicks with sub1=push_creative_14 — each one still carries its own click ID.

The two also differ in trust: sub IDs arrive from public click URLs, so anyone can put anything into them. Treat them as untrusted input for reporting, never as an attribution key.

In practice

The standard workflow is macro-to-sub-ID mapping: the traffic source expands its macros (say {site_id} and {creative_id}) into your link's sub1 and sub2, and your stats then break down by those values. Platforms that support per-campaign sub-ID labels (Affset lets you name sub1–sub5 per instance) turn cryptic report columns into readable ones like "placement" and "creative".

Related terms