1. Introduction

2. Data Augmentation Methods in NLP
2.1. Paraphrasing-based Methods
2.2. Noising
2.3. Sampling-based Methods
2.4. Analysis

3. Strategies and Tricks
3.1. Method Stacking
3.2. Training

4. Applications on NLP Tasks

5. Related Topics
5.1. Pretrained Language Models
5.2. Contrastive Learning
5.3. Other Data Manipulation Methods
5.4. Generative Adversarial Networks

6. Challenges and Opportunities

7. Conclusion