1 Introduction
2 What is federated analytics?
2.1 Federated learning vs. federated analytics
2.2 Applications for federated analytics
3 A taxonomy of federated analytics queries
3.1 Statistical testing
3.2 Private set queries
3.3 Matrix transformations
4 Existing solutions to statistical testing queries
4.1 Heavy hitters
4.2 Median
4.3 Key-Valued data
5 Existing solutions to set queries
5.1 Private set intersection
5.2 Private set union
5.3 Private cardinality testing
6 Existing solutions to matrix transformation
7 Challenges and Open Opportunities
7.1 Algorithmic security and privacy
7.2 Robustness to system failures
7.3 Participation incentive mechanisms
7.4 Decentralized and trust
7.5 Cross-silo federated analytics on the cloud
8 Conclusion