1 Introduction

2 Generalized OOD Detection
2.1 Anomaly Detection
2.5 Outlier Detection
2.7 Organization of Remaining Sections

3 OOD Detection: Methodology
3.1 Classification-based Methods
3.2 Density-based Methods
3.3 Distance-based Methods
3.4 Reconstruction-based Methods
3.5 Theoretical Analysis
3.6 Discussion

4 Methodologies from Other Sub-tasks
4.1 Open Set Recognition
4.2 Anomaly Detection & Novelty Detection

5 Benchmarks and Experiments
5.1 Benchmarks and Metrics
5.2 Experimental Setup
5.3 Experimental Results and Findings
5.4 Exclusion of Covariate-Shift Detection

6 Challenges and Future Directions
6.1 Challenges
6.2 Future Directions

7 Conclusion