Unsourced assertions ask readers to take your word for it. Phrases like "studies show" or "experts agree" with no link behind them read as filler, and they give search engines and AI answer engines no way to verify what you are saying.
Backing every meaningful claim with a link to a primary or authoritative source, such as official documentation, a standards body, peer-reviewed research, or the original dataset, builds reader trust and directly supports Google's E-E-A-T signals (Experience, Expertise, Authoritativeness, Trustworthiness).
It also matters for discovery. AI answer engines like ChatGPT, Gemini, and Google's AI Overviews prefer content whose claims are verifiable and well-sourced. Well-cited content is far more likely to be surfaced and cited back as the answer.
Citations do two jobs at once:
This is not just good manners. The Stanford Web Credibility guidelines (Stanford Persuasive Technology Lab) make it their first principle: "Make it easy to verify the accuracy of the information on your site... You can build web site credibility by providing third-party support (citations, references, source material) for information you present, especially if you link to this evidence." Google's guidance on creating helpful, reliable content says the same, asking whether content has "clear sourcing" and noting that of the E-E-A-T signals, "trust is most important."
Link to the closest thing to the origin of the fact:
Avoid citing a blog that cites a blog. Follow the chain back to the primary source and link that instead.