1 INTRODUCTION

2 RELATED SURVEYS  
2.1 Continual Learning  
2.2 Continual Learning for Computer Vision  
2.3 Continual Learning for NLP  
2.4 Continual Learning for Other Domains  

3 SETTINGS AND LEARNING MODES OF CL  
3.1 Basic Formulation  
3.2 Typical Scenarios  

4 OFFLINE CONTINUAL LEARNING  
4.1 Domain-Incremental Learning  
4.2 Task-Incremental Learning  
4.3 Class-Incremental Learning  

5 ONLINE CONTINUAL LEARNING  
5.1 Hard Task Boundary  
5.2 Blurry Task Boundary  

6 DATASETS  
6.1 Offline Datasets for NLP  
6.2 Online Datasets for NLP  
6.3 Offline CL Datasets for Multi-modal Tasks  
6.4 Offline and Online Datasets for Other Tasks  

7 METRICS  
7.1 Overall Performance  
7.2 Memory Stability  
7.3 Learning Plasticity  
7.4 Metrics for Continual Pre-training  
7.5 Online CL-Specific Metrics  

8 CHALLENGES AND FURTHER WORK  

9 CONCLUSIONS