Low-probability, high-impact events are those that have a low chance of occurring but would cause significant harm if they do. These events are often difficult to predict and quantify, but they can have a major impact on the organization's objectives, reputation, or operations. By including these events in a risk assessment, the organization can develop understandable and realistic risk scenarios that reflect the potential consequences of different outcomes1. This can help the organization to prioritize its risk management activities and allocate its resources accordingly.
References = Risk and Information Systems Control Study Manual, Chapter 5: Risk Assessment Process