TL;DR Summary of Top Websites Cited by AI Assistants in June 2025
Wikipedia is the most cited site across AI assistants, with ChatGPT referencing it the most. YouTube ranks highly in Perplexity and Google AI Overviews but is absent from ChatGPT’s top mentions. News sites like Reuters and Apple News are favored by ChatGPT, while user-generated content sites such as Reddit and Quora appear mainly in Google AI Overviews. Citation prominence is further analyzed using impression share and potential reach based on Google search volumes.
Optimixed’s Overview: Key Domains Influencing AI Assistant Responses in Mid-2025
Analysis of Website Mentions Across Leading AI Assistants
In an extensive study examining approximately 76.7 million AI overviews along with nearly 1 million prompts from ChatGPT and Perplexity each, the most frequently cited domains by AI assistants were evaluated for June 2025. The goal was to identify which websites AI systems rely on most, shedding light on favored information sources.
Top Cited Domains and Their Distribution
- Wikipedia leads all AI assistants, cited most by ChatGPT (16.3%), followed by Perplexity (12.5%) and Google AI Overviews (8.4%).
- YouTube is prominently mentioned in Perplexity (16.1%) and Google AI Overviews (9.5%) but does not appear in ChatGPT’s top 10.
- Reddit and Quora have notable presence only in Google AI Overviews, suggesting Google’s preference for user-generated content.
- News outlets such as Reuters and Apple News feature primarily in ChatGPT’s citations, highlighting its inclination towards current news sources.
- Health and medical sites like Mayo Clinic and Cleveland Clinic appear in Google AI Overviews, while niche health sites surface in Perplexity’s data.
Measuring Citation Impact: Impression Share and Potential Reach
Recognizing that not all citations hold equal weight, the study incorporated Google search volume data to estimate the visibility and potential exposure of cited websites. Two key metrics were calculated:
- Impression Share: Reflects mentions weighted by keyword search volume to gauge visibility.
- Potential Reach: Represents mentions weighted by overall Google search volume to estimate exposure potential.
This approach provides a more nuanced understanding of which domains have the greatest influence across different AI platforms.
Source: Data & Studies – SEO Blog by Ahrefs by Patrick Stox. Read original article.
