Docker comes in two flavours: The Comunity Edition (CE) and the Enterprise Edition (EE). See this question for the differences. Just take Docker CE if you don't know which to take.

There are two ways of installing it (thank you, Katu and Suor!). The official docker way is a bit more recent.

(A) Official Ubuntu Repositories

$ sudo apt-get install docker.io

In the past this way was discouraged as the docker package was super outdated. The universe sources are fairly recent now.

(B) Official Docker Way

The Ubuntu installation instructions list all you need in detail, but in most cases it boils down to:

(1) Set up the docker repository

sudo apt-get update
sudo apt-get install apt-transport-https ca-certificates curl software-properties-common
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

(2) Install Docker CE

sudo apt-get update
sudo apt-get install docker-ce

(3) Verify the installation

sudo docker run hello-world

The latest version can be found here. It was 18.06 in November 2018. This version is available in the sources from above, whereas the default Ubuntu package sources only contain Docker 1.5 (source). You can find changes in the docker release notes. Version 1.5 is so old that I could not find out how old it is.

I have managed to run docker on Ubuntu 16.10 as follows:

1.Update apt and install required certificates $ sudo apt-get update $ sudo apt-get install apt-transport-https ca-certificates 2. Add the GPG key to apt
$ sudo apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-keys 58118E89F3A912897C070ADBF76221572C52609D 3. Add the docker repo to the apt list echo "deb https://apt.dockerproject.org/repo ubuntu-xenial main" | sudo tee /etc/apt/sources.list.d/docker.list 4. Update apt sudo apt-get update 5. Check that the repo contains the docker installers

  $ apt-cache policy docker-engine

  docker-engine:
    Installed: 1.12.2-0~trusty
    Candidate: 1.12.2-0~trusty
    Version table:
   *** 1.12.2-0~trusty 0
          500 https://apt.dockerproject.org/repo/ ubuntu-trusty/main amd64 Packages
          100 /var/lib/dpkg/status
       1.12.1-0~trusty 0
          500 https://apt.dockerproject.org/repo/ ubuntu-trusty/main amd64 Packages
       1.12.0-0~trusty 0
          500 https://apt.dockerproject.org/repo/ ubuntu-trusty/main amd64 Packages

6. Install the docker engine

$ sudo apt-get install docker-engine

7.Start the docker daemon.

$ sudo service docker start

8. Verify that docker is installed correctly by running the hello-world image.

$ sudo docker run hello-world