Training large language models (LLMs) from scratch is resource-intensive, but fine-tuning pre-trained models offers a more accessible alternative with impactful results for specific tasks. Fine-tuning modifies a model's weights using gradient-based updates, enhancing performance and creativity, while Retrieval-Augmented Generation (RAG) incorporates documents into prompts for factual accuracy. Fine-tuning excels in creative and complex tasks, like structured output generation, and can mitigate model hallucinations. Key tools for fine-tuning include Hugging Face's transformers and Ludwig, with options for open-source or closed-source models. Challenges like out-of-memory errors can be addressed through parameter-efficient fine-tuning, quantization, and distributed training strategies. Effective data generation techniques and evaluation metrics are crucial for optimizing fine-tuning, with advancements in fine-tuning research focusing on reducing hallucinations and integrating with RAG systems. Ultimately, serving fine-tuned LLMs involves balancing latency, cost, and model versatility, with tools like LoRAX offering cost-effective deployment solutions.