The text discusses the concept of "model drift" in machine learning, which occurs when a trained model's performance worsens over time due to changes in real-world data distribution or other factors. Model drift can be caused by various factors such as changes in consumer behavior, data quality issues, and adversarial attacks. It can lead to decreased accuracy, poor customer experience, compliance risks, technical debt, and flawed decision-making. The text also highlights the importance of model monitoring, continuous retraining, and model versioning to mitigate model drift. Additionally, it emphasizes the need for selecting the right set of metrics to evaluate and monitor an ML system, setting up data quality checks, and leveraging automated monitoring tools. By applying these best practices, organizations can reduce the impact of model drift and build more robust, long-serving machine learning models for high-profile business use cases.