Understanding TrackingEvents, impression, click, and quartile
Purpose
This document explains the event terms and counting units that repeatedly appear in ad platform measurement, especially in VAST and video contexts.
Key Takeaways
impressionrepresents the point at which an ad is counted as shown or eligible to be shown.clickrepresents user interaction with the ad.quartileevents divide video playback progress into 25%, 50%, 75%, and 100% milestones.TrackingEventsrefers to the tracking URL set tied to those runtime events.impis a request-side object, whileimpressionis a runtime event, and that distinction should come first.
Event Flow
1. What impression means
- In display, it is often tied to creative render or a renderable state.
- In video, it is often tied to the point where playback can begin.
- The precise counting rule can vary by platform, SDK, or measurement vendor.
1-1. Request and exposure are different stages
| Stage | Main Event | Primary Owner |
|---|---|---|
| Request | imp creation | SSP or ad server |
| Win | win notice | SSP, DSP |
| Rendering | creative render | SDK, player, WebView |
| Exposure | impression | SDK, client tracker, player |
| Verification | viewability, verification | OMID, measurement vendor, SDK integration |
The practical point is that imp already exists at request time, while impression is only recorded after render-time exposure logic runs.
2. What click means
- It records that a user interacted with the creative.
- It can exist in both display and video flows, but collection points differ by runtime and vendor.
- Because click counts are much smaller than impression counts, filtering and duplication can have an outsized impact.
3. When quartiles matter
- Quartiles are mainly used in video measurement.
- A common sequence is
start,firstQuartile,midpoint,thirdQuartile, andcomplete. - Completion rate and drop-off analysis are usually derived from these events.
4. What TrackingEvents are
- In VAST, each event can map to one or more tracking URLs.
- The player or SDK calls those URLs when the event occurs.
- Accurate tracking therefore depends on creative markup, player logic, network calls, and server-side ingestion working together.
5. Why counts differ
- A player may emit an event while the network call fails.
- SSPs, DSPs, and measurement vendors may count the event at different points.
- Autoplay, mute, buffering, skip, and background transitions can all change runtime behavior.
Implementation Notes
- Event schemas should keep
event_name,event_time,creative_id,auction_id,placement_id, and device or session identifiers together. - Impression and quartile events often need idempotency handling because duplicates and retries are common in video runtimes.