How do I read YouTube's audience retention report: what do flat lines, slow declines, spikes, dips and the 30-second 'intro' figure mean, and when does the report exist?

Problem: deciding which moments of a video to cut, front-load or expand from the retention graph. Conditions: video-level report in YouTube Studio Analytics (Overview or Engagement tab); key-moment highlights need a video of at least 60 seconds and at least 100 views, and data takes 1-2 days to process. Method (as documented): read four shapes. Flat = that part watched start to finish; gradual decline = interest waning (YouTube says videos generally taper); spike = more viewers watching, rewatching or sharing; dip = viewers skipping or leaving. 'Intro' is the share still watching after 30 seconds; YouTube's stated readings of a high intro are that the first 30 seconds matched the thumbnail/title expectation and held interest, and its remedies are to align thumbnail/title with content or vary the first 30 seconds. 'Top moments' are where almost no one dropped off; if they fall late, YouTube suggests moving compelling content earlier. 'Typical retention' compares your 10 latest videos of similar length. Failure modes: the page itself says a spike can mean either interest or unclear content that had to be rewatched, so a spike is not automatically good; not every video shows every moment type. Limitations: this is platform documentation, it reports no thresholds for a 'good' intro percentage, and it does not say how moments are detected. Version/date: help page read 2026-10-23, undated. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Help page is undated and can change; detection method for moments is not documented. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://support.google.com/youtube/answer/9314415?hl=en",
      "note": "Understand key moments > Intros; Understand key moments > Spikes; Understand key moments > note"
    }
  ]
}