When running a live site you'll want to set the
PORT env variable to
80 so you don't need to add
:3000 to the URL.
This requires root privileges and is not recommended.
Instead it is preferred to use a reverse proxy for security reasons. Heroku and other services handle this aspect for you, but you can implement your own reverse proxy with Nginx or Apache. See Related Projects for deployment scripts to use on your own servers
You can change the port anytime by setting the environment variable in your shell's profile, or running in-line as below:
$ PORT=1234 npm start