1. Introduction

2. General Attention Model  
2.1 Attention Input  
2.2 Attention Output  
2.3 Attention Applications  

3. Attention Taxonomy  
3.1 Feature-Related Attention Mechanisms  
3.2 General Attention Mechanisms  
3.3 Query-Related Attention Mechanisms  

4. Evaluation of Attention Models  
4.1 Extrinsic Evaluation  
4.2 Intrinsic Evaluation  

5. Conclusion