This chapter analyzes the anonymity of Bitcoin, a peer-to-peer electronic currency system. The authors construct two networks from Bitcoin's public transaction history: the transaction network and the user network. They explore the topological structures of these networks, which have non-trivial properties and provide complementary views of the Bitcoin system. The analysis combines these structures with external information and techniques such as context discovery and flow analysis to investigate a case of alleged Bitcoin theft. The study reveals that while Bitcoin attempts to prevent de-anonymization by storing the mapping of a user to their public keys on their node and allowing multiple public keys, the networks' structures and external information can still lead to de-anonymization. The chapter concludes by discussing the implications of these findings for the system's anonymity and the challenges in mitigating these risks.This chapter analyzes the anonymity of Bitcoin, a peer-to-peer electronic currency system. The authors construct two networks from Bitcoin's public transaction history: the transaction network and the user network. They explore the topological structures of these networks, which have non-trivial properties and provide complementary views of the Bitcoin system. The analysis combines these structures with external information and techniques such as context discovery and flow analysis to investigate a case of alleged Bitcoin theft. The study reveals that while Bitcoin attempts to prevent de-anonymization by storing the mapping of a user to their public keys on their node and allowing multiple public keys, the networks' structures and external information can still lead to de-anonymization. The chapter concludes by discussing the implications of these findings for the system's anonymity and the challenges in mitigating these risks.