Multilingual SEO is the discipline of making a single brand discoverable, trustworthy and citable in every language and market it operates in — without diluting itself in any of them.
The work covers international SEO (geography), language-level SEO (translation, localization, market intent), and the increasingly important multilingual entity layer — making sure ChatGPT, Perplexity, Gemini and Google AI Overviews recognise your brand as one entity, regardless of the language of the question.
Done well, multilingual SEO is invisible to users and unmissable to search engines. Done poorly, it duplicates content, breaks hreflang, fragments authority and leaves your strongest market subsidising your weakest.