This repository is the companion code for the O'Reilly book 'Hands-On Large Language Models' by Jay Alammar and Maarten Grootendorst. It provides 12 chapters of Jupyter notebooks covering fundamental and advanced LLM topics including tokenization, embeddings, text classification, clustering, prompt engineering, semantic search, multimodal models, fine-tuning, and generation. All notebooks are designed to run on Google Colab with free GPU resources and rely heavily on Hugging Face libraries (transformers, datasets, sentence-transformers, TRL) and external APIs (OpenAI, Cohere). The code is educational in nature, with clear step-by-step explanations and visualizations. While it is not a production application or a novel research pipeline, it serves as a high-quality, reproducible tutorial resource for practitioners learning LLM workflows. The repository includes pinned dependencies, Conda environment setup, and local installation guides, making it relatively easy to reproduce in a controlled environment, though API keys are required for some sections.