Docker Swarm is Docker's native container orchestration solution, built directly into Docker Engine, that transforms a pool of Docker hosts into a single virtual system. Unlike external orchestrators, Swarm mode leverages familiar Docker concepts and commands while adding cluster management, service discovery, load balancing, and zero-downtime deployments. It uses the Raft consensus algorithm to maintain cluster state across manager nodes, ensuring high availability without external dependencies. Keep in mind that Swarm operates on a declarative model — you define the desired state of services, and the orchestrator continuously works to maintain that state, automatically recovering from failures and distributing workloads.