The article explains the mathematical concepts necessary to understand Large Language Models (LLMs), specifically vectors, high-dimensional spaces, and embeddings. It discusses how these concepts are used to represent likelihoods and meanings in LLMs. The article aims to provide a foundation for understanding LLMs, but notes that it only covers the basics and that true understanding requires more in-depth knowledge. The author also distinguishes between the 'messy' unnormalised space and the neat, tidy normalised one, where probabilities are used to represent likelihoods.