I. Introduction  
A. Foundation of Loop Closure Detection  
B. Paper Organization  

II. Visual Place Recognition  

III. Simultaneous Localization and Mapping  
A. Localization  
B. Mapping  
C. Sensing  

IV. Structure of a Visual Loop Closure Detection System  

V. Feature Extraction  
A. Hand-Crafted Feature-Based Representation  
B. Learned Feature-Based Representation  

VI. Looking Behind  
A. Environment Representation  
B. Location Indexing  

VII. Decision Making  
A. Matching Locations  
B. Exploiting the Temporal Consistency  
C. Is the Current Location Known? The Geometrical Verification  

VIII. Benchmarking  
A. Evaluation Metrics  
B. Datasets  

IX. New Challenges: Long-term Operation  
A. Dynamic Environments  
B. Viewpoint Variations  
C. Map Management and Storage Requirements  
D. Computational Complexity  

X. Conclusion