The article asks about the best approach to train a custom large language model (LLM) or ChatGPT on a set of documents in December 2023. A previous thread on the topic is mentioned, but it may be outdated. The question is about how to teach an LLM to answer questions using a custom set of documents. This can be achieved through methods like Retrieval-Augmented Generation (RAG) rather than training a model from scratch.