> ## Documentation Index
> Fetch the complete documentation index at: https://wiki.platelunchcollective.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Impression Share

> Impression share is the portion of available appearances a brand actually captures for a set of queries, measuring presence against the ceiling of possible presence.

*Measurement* · *Citation & Visibility Measurement*

## Definition

Impression share is the portion of available appearances a brand captures for a given set of queries, measured against the total it could have captured. Where a raw count says how often a brand showed up, impression share says how often it showed up out of every time it could have. It measures presence against a ceiling rather than in isolation.

## Why It Matters for AI Search

In answer engines the ceiling is different from the one search advertising defined. A generated answer names a handful of sources, not a page of ten blue links, so the available appearances for any query are few and the competition for them is sharp. Reading visibility as a share of that scarce space, rather than as a total, is what makes it comparable across queries and over time. Share of model applies the same logic to how often a brand is the one a system reaches for, and both reframe visibility as a contest for limited room rather than a tally.

## Related Terms

<CardGroup cols={2}>
  <Card title="Share of model" href="/ai-search-glossary/share-of-model">See also</Card>
  <Card title="SERP" href="/ai-search-glossary/serp">See also</Card>
  <Card title="Featured snippet" href="/ai-search-glossary/featured-snippet">See also</Card>
  <Card title="Brand authority" href="/ai-search-glossary/brand-authority">See also</Card>
</CardGroup>

## Relevant Plate Lunch Collective Services

[AI Search Visibility Assessment](https://www.platelunchcollective.com/services/consulting/ai-search-visibility)  [AI SEO](https://www.platelunchcollective.com/services/ai-seo)