This document discusses using Vagrant and Docker together to build portable development environments. It provides an overview of Vagrant and Docker, including how Vagrant uses boxes and providers to manage virtual machines and containers. It then shows how to set up a sample Vagrantfile to provision a Docker container for development. Key steps include installing Vagrant, initializing a project directory, selecting a box, editing the Vagrantfile to specify the box and Docker configuration, and running vagrant up to launch the environment.