What does Performance Mean for Large Language Models?

In the last decade there has been a significant leap in the capability of foundation AI models, largely driven by the introduction and refinement of transformer-based machine learning architectures. The most visible consequence of this has been the explosion of interest and application of large language models such as ChatGPT. This is one exemplar of how a foundation model trained on a huge amount of data can be specialised for particular task, often by a phase of reinforcement learning with human feedback.