Define Overfitting

Overfitting is a machine learning phenomenon where models learn training data patterns too specifically, including noise and random fluctuations, resulting in excellent training performance but poor generalization to new data. This occurs when models become overly complex relative to the available training data, memorizing specific examples rather than learning underlying patterns that apply broadly. Overfitting manifests as a large performance gap between training and validation datasets, where training accuracy remains high while validation accuracy plateaus or degrades. Common causes include excessive model complexity, insufficient training data, lack of regularization, and prolonged training without proper validation monitoring. Detection methods include cross-validation, learning curves analysis, and train-validation performance comparison. Prevention techniques encompass regularization (L1/L2 penalties, dropout), early stopping, data augmentation, ensemble methods, and model simplification. For AI agents, preventing overfitting ensures reliable decision-making across diverse real-world scenarios beyond training conditions.