So let's get NGINX installed on our machine!

 By default, the nginx package should already be in Ubuntu's default repositories:

hobnob@hobnob:$ apt-cache show nginx
Package: nginx
Architecture: all
Version: 1.14.0-0ubuntu1
...

However, we should use the official NGINX repository to ensure we always get the most up-to-date version. To do this, we need to add NGINX's package repository to the list of repositories that Ubuntu will search for when it tries to download packages.

By default, there are two places that Ubuntu will search: inside the /etc/apt/sources.list file and inside files under the /etc/apt/sources.list.d/ directory. We should not write directly to the /etc/apt/sources.list file because when we upgrade our distribution, this file will be overwritten. Instead, we should create a new file with a unique name inside the /etc/apt/sources.list.d/ directory, and add the entry for the NGINX repository:

hobnob@hobnob:$ echo "deb http://nginx.org/packages/ubuntu/ bionic nginx" | sudo tee -a /etc/apt/sources.list.d/nginx.list
hobnob@hobnob:$ echo "deb-src http://nginx.org/packages/ubuntu/ bionic nginx" | sudo tee -a /etc/apt/sources.list.d/nginx.list

To ensure the integrity and authenticity of the package they download, the Ubuntu package management tools (dpkg and apt) require package distributors to sign their packages using a publicly available GPG key. Therefore, we must add this key to APT so that it knows how to check the integrity and authenticity of the packages:

hobnob@hobnob:$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys ABF5BD827BD9BF62
hobnob@hobnob:$ sudo apt update && sudo apt install nginx

NGINX is now installed, but it is not yet running:

hobnob@hobnob:$ sudo systemctl status nginx.service
● nginx.service - nginx - high performance web server
   Loaded: loaded (/lib/systemd/system/nginx.service; enabled; vendor preset: enabled)
   Active: inactive (dead)
     Docs: http://nginx.org/en/docs/