What is the difference between a directory on a physical machine and a volume in a Docker container?

A directory on the physical machine is a regular folder in the host's filesystem where files are stored.

A Docker volume is a special mechanism for storing data that:

• Is isolated from the container's lifecycle (data persists even after the container is deleted).
• Is managed by Docker and optimized for container operation.
• Can be mounted into one or multiple containers simultaneously.

Unlike simple host directory mounting, volumes provide better portability and data management. For example, a volume can be created with the command:

docker volume create my_volume

And used in a container with:

docker run -v my_volume:/app/data my_image

Thus, volumes are convenient for storing persistent data, while host directories are suitable for quick access to local files but offer less isolation.