Chapter 7 · Part 4
Where this shows up
Embeddings are the least flashy idea in AI and quietly one of the most used. Turn anything into a vector where closeness means similarity, and a huge range of products become a nearest-neighbor lookup. You've been using embeddings all day without seeing them.
Here's where "meaning as a place in space" pays off.
Semantic search — find things by meaning, even with no shared keywords.
The same idea, many jobs
All of these reduce to embed-then-compare:
- Search and recommendations rank everything by cosine similarity to a query or to what you liked (semantic search).
- RAG — the retrieval behind modern chatbots — embeds your question, finds the closest documents, and hands them to an LLM so it can answer from real sources.
- Multimodal search works because text and images can share one space (CLIP).
- Moderation and dedup treat "too similar to known-bad" as a signal.
That's the course
You built it from the ground up: a word becomes a vector, closeness means similarity, the vectors are learned from context, they support arithmetic, anything can be embedded, and nearest- neighbor lookup powers search and recommendations.
If you enjoyed this, the other courses show these embeddings at work — in recommender feeds, chatbots, and image models.