Fun note about their logo, it’s a whale with shipping containers. Matching perfectly with the core idea of the product.
Docker is software that can package other software in a concept called a Docker Container. This container is portable across many different operating environments such as Linux and Windows.
Docker provides a way to isolate the container environment (the Guest machine) from the operating system (the Host machine).
This allows for many different kinds of software and operating environment to run within the containers without interfering with the host machine.