Deep Dive / 12 min read

How Perplexity, ChatGPT, and Gemini Actually Source Brand Mentions

A technical deep dive into the retrieval pipelines that find, score, and cite brand facts in modern generative answers.

GenRankEngine Engineering
November 5, 2025

Modern generative engines do not simply guess answers. They combine retrieval from large knowledge stores with a language model that synthesizes text. The retrieval layer determines what facts are available to the model in the first place. If your brand is not surfaced by retrieval, it will not be considered during synthesis.

The Canonical Retrieval Pipeline

Across many systems the pipeline follows the same broad stages:

01
Indexing: Crawling web pages and creating searchable indexes.
02
Vectorization: Converting text into dense vectors for semantic search.
03
Retrieval: Selecting candidate passages (Vector vs Lexical).
04
Reranking: Scoring candidates by relevance, authority, and recency.
05
Generation: Synthesizing the answer with citations.

Key technical building blocks

Indexing and freshness

The index is the foundation. Systems with faster or more frequent crawls can reflect recent product changes and press mentions more quickly. Perplexity and Google publish information about frequent reindexing and real time sources for certain features.

Embeddings and vector stores

Embedding models map text to vectors. Vector stores then allow fast nearest neighbor search. Retrieval quality depends heavily on embedding alignment to the retrieval task.

Note: Different embedding models shift which passages are considered closest. This changes which brand mentions appear as candidates.

Retrieval strategies

  • Pure vector retrieval: Good for semantic meaning, bad for exact keywords.
  • Lexical retrieval: Traditional search (BM25). Precise for exact phrases/names.
  • Hybrid retrieval: Combines both. Most production systems use this.

How Engines Differ in Practice

Perplexity

Focuses on transparent sourcing and research. Heavy citation usage.

ChatGPT Search

Exposes web retrieval via plugins/browsing. Uses live web signals.

Google Gemini

Tied to massive web index. AI Overviews summarize search results.

Reranking signals that matter

Reranking is where business signals influence visibility.

  • Authority: Source reputation and domain history.
  • Recency: Fresh pages score higher.
  • Coverage: Specific, concrete claims are valued.
  • Consistency: Matches between structured data and text.

Practical implications for brands

1. Make brand facts explicit

Create canonical signal pages (e.g., /about) with clear schema markup.

2. Ensure cross source corroboration

Get mentions in reputable publications and review sites. Repetition increases confidence.

3. Use focused content

Deep explainers on narrow topics outperform generic articles for retrieval specificity.

4. Keep pages fresh

Update changelogs and docs with visible dates. Recency influences reranking.

Measuring where you appear

Create a set of 30-60 buyer-oriented prompts. Query each engine and record if your brand appears, how it is cited, and if a link is provided.

# Example Prompt
What are reliable AI visibility tools for measuring brand mentions across ChatGPT, Perplexity, and Google Gemini?

Quick Checklist for Technical Teams

  • Publish machine-readable brand facts page.
  • Add Organization/Product schema.
  • Produce one deep explainer with citations.
  • Maintain accessible changelog.

Establish your baseline

Run a small visibility test with a set of buyer prompts across ChatGPT, Perplexity, and Google Gemini.

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