Cortana vs Docker

You can ask Cortana what music is playing and she will attempt to identify it.

Cortana monitors your Bing search history, social network actions, music played, etc to find out what are your favorite artists and will let you know if they plan to play in your area.

Docker creates a single object, containing an application with its dependencies, that can be moved between any docker-enabled machines, guaranteeing the same environment for application execution.

Docker tracks changes in systems. It allows for commits and rollbacks and for quick deployment due to having to deploy only the updated code.

Docker essentially allows creating boilerplate systems (a LAMP stack, for example) that can be used as a starting point on multiple projects. And you can find multiple such containers already created by people in their public registry.

Allows automatically assembling a container from its source code.

Docker allows easily pushing and pulling containers to and from their public index.docker.io registry. Additionally, dotCloud maintains a list of official repositories of the more popular containers.

You can set up Docker within an already virtualized environment such as a virtual machine. This allows you to run Docker on Mac and Windows, among other use-cases.

Docker can be used with OpenVZ, systemd-nspawn, libvirt-lxc, libvirt-sandbox, qemu/kvm, BSD Jails, Solaris Zones, and chroot.