HotStuff is a leader-based Byzantine fault-tolerant replication protocol designed for the partially synchronous model. It achieves two key properties: linear view change and optimistic responsiveness. In the linear view change phase, a correct leader can drive the protocol to consensus with communication complexity linear in the number of replicas, even after a global stabilization time (GST). Optimistic responsiveness ensures that the leader can make progress in time depending only on actual message delays, independent of worst-case delays. HotStuff introduces a second phase that allows replicas to change their minds after voting, simplifying the leader replacement protocol. The protocol is efficient, scalable, and practical, making it suitable for building large-scale replication services. It supports frequent leader rotation, which is beneficial for blockchain contexts to ensure chain quality. The protocol is based on threshold signatures and cryptographic primitives, ensuring safety and liveness. The implementation of HotStuff is straightforward due to its simplicity, and it can be pipelined for improved performance.HotStuff is a leader-based Byzantine fault-tolerant replication protocol designed for the partially synchronous model. It achieves two key properties: linear view change and optimistic responsiveness. In the linear view change phase, a correct leader can drive the protocol to consensus with communication complexity linear in the number of replicas, even after a global stabilization time (GST). Optimistic responsiveness ensures that the leader can make progress in time depending only on actual message delays, independent of worst-case delays. HotStuff introduces a second phase that allows replicas to change their minds after voting, simplifying the leader replacement protocol. The protocol is efficient, scalable, and practical, making it suitable for building large-scale replication services. It supports frequent leader rotation, which is beneficial for blockchain contexts to ensure chain quality. The protocol is based on threshold signatures and cryptographic primitives, ensuring safety and liveness. The implementation of HotStuff is straightforward due to its simplicity, and it can be pipelined for improved performance.