1. INTRODUCTION  
2. PROBLEM SETTING AND CATEGORIZATION  
2.1 Problem Definition of OOD Generalization  
2.2 Categorization of OOD Evaluation  
3. OOD PERFORMANCE TESTING  
3.1 Designing Datasets and Benchmarks  
3.2 Analyzing Performance and Shifts  
4. OOD PERFORMANCE PREDICTION  
4.1 Performance Prediction using Model Output Properties on Test Data  
4.2 Distribution Discrepancy based Performance Prediction  
4.3 Model Agreement based Performance Prediction  
5. OOD INTRINSIC PROPERTY CHARACTERIZATION  
5.1 Distributional Robustness  
5.2 Stability  
5.3 Invariance  
5.4 Flatness  
6. DISCUSSION ON PRETRAINED MODELS  
7. CONCLUSION AND FUTURE DIRECTIONS