What is semantic search?
PICTURE THIS: 1, 2, 2, 8
Simple meaning
Semantic search ranks documents by meaning rather than exact keyword overlap.
WHY — Tokens instead of words?
LLMs use tokens (not full words) because it helps them:
who only read docs from people who shipped.
and tied to GenAI / LLM work.
Each piece maps to a number the network can learn.
Fixed pieces are what transformers expect as input.
STEPS — What happens with tokens?
Before the model can read a sentence, it goes through these steps:
- 1Semantic search ranks documents
by meaning rather than exact keyword overlap.
- 2A query and a
passage can match if their embeddings are close.
- 3It is the retrieval
style most RAG systems start with.
- 4Context mix
Attention looks at nearby tokens together.
- 5Next token
The model scores what should come next.
- 6Decode
IDs turn back into readable text.
EXAMPLE — See it in action
Let's see how a real sentence is tokenized (tokens may vary by model):
Note: Actual tokens and IDs depend on the tokenizer (e.g., GPT, Llama, etc.).
Key takeaway
Semantic search ranks documents by meaning rather than exact keyword overlap. A query and a passage can match if their embeddings are close.