Installation on macOS
The Homebrew Cask docker-desktop (canonical token) installs Docker Desktop, which bundles the engine, the client, Compose, and a graphical interface. Note: brew install docker WITHOUT the --cask option installs the CLI only (formula), not the Docker Desktop application. After installing with brew, you must launch the application at least once: it starts a lightweight Linux virtual machine (via Apple's virtualization framework) in which the daemon runs. As long as the application is not launched, docker ps returns a connection error to the daemon.
Accept the system authorization requested on first launch: Docker Desktop needs a privileged component to manage the socket and networking.
Once the application is launched, verify that the engine responds. docker --version only prints the client version; to prove the daemon is actually working, run docker run --rm hello-world (without sudo). This command pulls a small image, starts a container, and removes it immediately.
Apple Silicon and architectures
On Apple Silicon Macs (M1/M2/M3…), containers run in arm64 by default. To run an amd64 (x86_64) image, use the platform option, for example docker run --platform linux/amd64 …. By default, this emulation relies on the QEMU software emulator. Rosetta is only used if you explicitly enable the corresponding option in Docker Desktop's settings; it is therefore not used automatically. Either way the emulation works but is slower; prefer multi-architecture images whenever possible.
Common pitfalls
Do not confuse the docker-desktop Cask (Docker Desktop) with the CLI formula. If you had installed the docker formula (client binary only, via brew install docker without --cask), it may conflict in the PATH. Check with which docker that the command really points to the Docker Desktop installation.