What is the role of containerd and runc in the Docker architecture?

containerd is a daemon that manages the container lifecycle (pulling images, managing storage, supervising execution) and sits between the Docker daemon (dockerd) and the low-level runtime. runc is the actual OCI-compliant low-level runtime that creates and runs containers using namespaces/cgroups directly. dockerd delegates to containerd, which delegates to runc for each container.