"Docker is an operating system virtualization technology that allows applications to be packaged as containers. This is a very fundamental part of cloud computing, as containerized applications can be run on any type of infrastructure, regardless of the provider. This prevents vendor lock-in and allows applications to be ported between providers. A docker container is built by using Dockerfile that specifies all of the layers that describe an application. These are items like the base operating system, the directory where the application lives, and other dependencies that require an application to work. Docker containers are then deployed to infrastructure like AWS EC2 or to Kubernetes which is responsible for scheduling how many containers need to be run and how many instances of servers need to be available to run an application."
in other words
A robot that automatically deploys applications.