Semantic topic coverage means that a text contains the concepts, entities and sub-questions that naturally belong to the given topic, rather than just a repeated keyword. Search engines and language models alike judge content by whether it answers related questions and mentions things an expert on the topic would have to mention – specific procedures, deadlines, exceptions, costs, or responsible institutions. Gaps can be identified by comparing with content that ranks in the results, by looking at users' related questions, and by talking to people who deal with the topic in practice. Filling in the missing parts tends to be more effective than writing a new article. The goal is not length: a text that covers the topic briefly and precisely will beat a lengthy article without specific information.
See also: Content gap in retrieval, Information gain, Topical authority.
