Gradual forgetting is a machine learning technique used in dynamic environments and streaming data processing where the influence of past observations or previously learned knowledge is progressively reduced over time to adapt to evolving data distributions and concept drift. Instead of abruptly discarding all historical information, the system applies continuous decay factors or time-dependent weighting functions that assign greater significance to newer data points while smoothly diminishing the impact of older records. This mechanism enables predictive models to continuously track shifting trends and update their parameters to reflect the current state of non-stationary environments without destabilizing performance through abrupt data loss.