Embeddings

Dense vector representations are the bridge between raw text and everything that follows in this repo: semantic search, vector databases, RAG, clustering, retrieval evaluation, and recommendation-style systems.

What To Learn Here

• How text is mapped into dense vectors
• Why cosine similarity is the default comparison metric
• The difference between word, token, sentence, and sparse embeddings
• When to use local models vs hosted APIs
• How embeddings become a practical search pipeline

Recommended Order

1. 01_START_HERE.ipynb
2. 02_embeddings_intro.ipynb
3. 12_semantic_similarity.ipynb
4. 06_sentence_transformer_intro.ipynb
5. 10_huggingface_embeddings.ipynb
6. 11_openai_embeddings.ipynb
7. 04_semantic_search_intro.ipynb
8. 13_vector_database_demo.ipynb
9. 09_embedding_comparison.md

Optional depth:

• 05_semantic_textual_similarity_intro.ipynb
• 03_paraphrase_mining_intro.ipynb
• 07_sparse_encoder_intro.ipynb

Learning Goals

By the end of this phase, you should be able to:

• Explain why embeddings make semantic retrieval possible
• Generate embeddings with both local and API-based workflows
• Compare pooling strategies at a high level
• Build a minimal semantic search flow
• Choose an embedding approach based on quality, latency, and cost constraints

Recent 2026 Topics To Keep In View

This phase is centered on text embeddings, but production retrieval systems in 2026 also depend on:

• Multimodal embeddings such as CLIP and SigLIP for image-text retrieval
• Dense + sparse + reranker pipelines instead of dense-only retrieval
• Late-interaction retrieval patterns such as ColBERT-style reranking
• Local embedding stacks for privacy-sensitive workflows alongside hosted APIs
• Embedding versioning, drift tracking, and compression for large-scale vector systems

Prerequisites

• Tokenization fundamentals from 04-token/
• Basic linear algebra intuition from 03-maths/
• Enough Python to run notebooks and inspect arrays

Good Study Strategy

• Do not treat every notebook as mandatory on the first pass.
• Focus first on concept transfer: similarity, search, and trade-offs.
• Return later for sparse retrieval and model-comparison detail when you start Phase 6 and Phase 7.

What To Build After This

• A semantic FAQ search system
• A duplicate-detection tool for documents
• A chunk-and-retrieve pipeline that feeds Phase 8 RAG work
• An image-text search prototype using multimodal embeddings
• A hybrid retrieval stack with a reranker on top of dense retrieval

Companion Files

• 08_QUICKSTART.md: fast setup and notebook entry points
• 09_embedding_comparison.md: decision support for local vs hosted embedding stacks

What Comes Next

• Continue to ../07-vector-databases/README.md to learn how embeddings become retrievable infrastructure.
• Continue to ../08-rag/README.md to use embeddings inside full retrieval systems.
• Continue to ../13-multimodal/README.md later if you want image-text and cross-modal embedding systems.