The Vagrantfile specifies the environment as a combination of a base box, VM settings and optionally a provisioning script/recipe/whatever to run. The base box

The Vagrantfile specifies the environment as a combination of a base box, VM settings and optionally a provisioning script/recipe/whatever to run. The base box is only stored once, and individual VMs for projects are created from that box and destroyed when you don't need them any more. It's common to use something like Chef or Puppet to provision the software that you actually need for each project rather than just put everything in the base box, but the author chose to just make an all-inclusive box instead.