Semantic search
Semantic search finds content by what it means, so a page can match a question even when it uses different words.
Semantic search finds content by what it means, even when the words differ. A question about "keeping coffee fresh" can find a page about "storing beans in an airtight tin," even though they share almost no words. Most AI platforms use some form of it to find the passages they answer from.
For marketers, it changes what a good match is. Repeating a keyword matters less. Covering the idea clearly, in the words your customers would recognise, matters more.
How it works
The system turns each passage into a list of numbers that captures its meaning, called an embedding. It does the same with the question. Passages whose numbers sit close to the question's are judged to mean something similar, and they're returned first.
This is why a page can match a question it never mentions word for word. It's also why a page can miss a question it repeats. If the passage around the words is about something else, its meaning doesn't line up.
An example
Someone asks "Which tea is good before bed?" Harrow & Pine has a page with "bedtime tea" in its title, but the text is mostly about the brand's history. Another site has a paragraph that never says "bedtime," and explains which herbal teas have no caffeine and help people wind down in the evening. The second passage is closer in meaning to the question, so it's the one found.
Writing for it
Answer the actual question, plainly, near the top of a section. Use the different words people use for the same thing, where it reads naturally. And keep each section on one subject, so its meaning is clear instead of blurred by everything else on the page.
Many platforms mix semantic search with ordinary keyword search, so the exact words still help. They just aren't enough on their own.
In AnswerOrbit
The Pages tab in Sources shows which pages the answers used for your prompts. Reading the passages that win can show you how closely they answer the question compared with yours.