1. Introduction  
2. Structural Characteristics  
2.1. Vertices  
2.2. Meso-level  
2.3. Network Density  
3. Big Network Models  
3.1. Static Network Model  
3.2. Motif-based Network Model  
3.3. Community Detection in MLNs  
4. Technologies in Big Networks  
4.1. Ranking Algorithms  
4.3. Network Embedding Methods  
5. Big Network Applications  
5.1. Community Detection  
5.2. Link Prediction  
5.3. Recommendation  
6. Open Issues and Challenges  
6.2. Computational Complexity  
6.3. Higher-order Network Blocks  
7. Conclusion