What is the Docker daemon?

The Docker daemon (dockerd) is the long-running service that manages Docker objects and performs operations such as building images, creating containers, configuring networks, and mounting volumes. The docker command-line client normally sends requests to that daemon through a local socket or a configured context.

docker info
docker context show

A “Cannot connect to the Docker daemon” error can mean the service is stopped, the client is using the wrong context, or the socket permissions are wrong. It is different from docker: command not found, which means the client itself is unavailable.

On Docker Desktop, the desktop application manages the engine. On a Linux Engine installation, a service manager commonly manages dockerd. Do not expose the Docker socket or a remote daemon to an untrusted network: access to it is effectively high privilege. Use documented TLS, rootless mode, or a controlled local socket when remote access is genuinely required.

Sources

• Docker documentation
• Docker CLI reference