OpenAI has introduced fine-tuning and API updates for GPT-4, enabling developers to customize the model for specialized tasks, such as aligning with a brand's voice or formatting API responses as JSON. The fine-tuning feature allows for improved performance in specific use cases, like customer service and advertising, by adapting the model to produce unique and deliberate user experiences. The process involves data preparation, cleaning, and formatting in JSONL files, followed by uploading the data via API and initiating a supervised fine-tuning job. Once fine-tuned, the model's performance can be evaluated and integrated into applications. Tools like Klu.ai simplify this process, aiding in prompt engineering and deployment. Fine-tuning is an iterative process that requires continuous monitoring to maintain model quality, and it incurs costs based on token usage.