In our book, we explore in detail the working principles of artificial intelligence, LLM models, how these models can be trained, the training environment, how to prepare training data, and how to write the training code. We will learn in detail how to set up the training environment, use various Transformers libraries, train large LLM models through quantization (LoRA and QLoRA), create datasets in different formats, and grasp the mathematical foundations of artificial intelligence.