What is Co-Citation?
Co-citation is when two brands, websites or documents are mentioned together by a third source, even if they never link to each other. The more often independent sources name them side by side, the more strongly search engines and AI models associate the two.
The idea comes from bibliometrics, the study of academic citations, where two papers count as related when other papers often cite them together. SEO specialists later used the term for websites and brands that appear together on the same pages. For AI, the principle is similar: language models learn which brands belong together from how the web discusses them.
A close relative is co-occurrence: your brand name appearing near specific topics or phrases, such as "payroll software for small businesses". Together, co-citation and co-occurrence shape which category a model places you in and which competitors it treats as your peers.
Why co-citation matters for AI visibility
When someone asks an AI assistant for the best options in a category, the model draws on patterns it has seen in text. Brands that comparison articles, review sites and forum threads repeatedly discuss next to the category leaders are more likely to end up in that consideration set and earn AI brand mentions. A brand that is never discussed alongside them may not register as a real alternative, however good its product is.
Co-citation can also work against you. If your brand keeps appearing next to the wrong category, an old product line or a controversy, AI models can repeat that association in their answers.
How to build useful co-citations
Find the lists that matter. Look for the comparison articles, "best of" lists and review pages that AI answers cite for your category prompts.
Earn a place in them. Pitch editors, offer data or product access and use digital PR to appear where your competitors already are.
Be consistent about your category. Describe what you do in the same words across your site, profiles and press materials, so third parties repeat it. Entity optimization helps here.
Monitor who appears next to you. The competitors AI models name alongside you show how they group your market. Competitor benchmarking makes this visible over time.
The article on how AI models decide which brands to recommend explains the wider mechanism. Trackbase shows which competitors appear in the same AI answers as your brand, across 11 AI models.
Examples of co-citation
A Dutch project management tool gets included in an independent "best tools for agencies" article next to two market leaders, the kind of placement that helps models see it as a real alternative.
A sustainable sneaker brand keeps appearing in fast-fashion roundups, so AI answers group it with the wrong segment until it earns coverage next to other sustainable brands.
An HR software vendor notices that ChatGPT always names it together with a competitor that has a similar name, and it sharpens its positioning on its site and in press materials.
A regional law firm is listed next to national firms on a legal directory's page of employment law specialists, which strengthens its link to that practice area.
Frequently asked questions
What is the difference between co-citation and co-occurrence?
Co-citation is about entities being mentioned together: two brands or websites named by the same third source. Co-occurrence is about words appearing close together, such as your brand name near a phrase like "accounting software for freelancers". Both help search engines and AI models understand which category you belong to and which alternatives are comparable.
Is it bad to be mentioned alongside competitors?
Usually not. Being named next to established competitors signals that you belong in the same category, which is exactly what you need to appear in AI answers about that category. It only becomes a problem when the context is negative, for example when sources consistently describe you as the cheaper but weaker alternative.
How do I find co-citation opportunities?
Run your category prompts in several AI assistants and note which sources they cite and which brands they name. Then check the cited comparison articles, directories and review sites. Where competitors are listed and you are not, you have a concrete opportunity. Prioritize sources that show up across several models and prompts.