Docker cp is a command used to copy files and directories between your host system and Docker containers, similar to the Unix cp command but with some differences in behavior. The basic syntax of docker cp is $ docker cp <src> <dest>, where <src> and <dest> can reference paths on your local filesystem or within a container. It's not possible to copy files directly between containers, but you can achieve this by running docker cp twice. Understanding the different behaviors of docker cp is crucial for using it effectively in various scenarios such as debugging container issues, copying out or backing up stored files, and making config file changes.