Docker is a technology for packaging applications for easy deployment.
Dockerizing your Application
You should create a Docker file, which encapsulates your application. You can read more about Dockerizing a NodeJS application in the NodeJS Documentation.
Compose is a tool for defining and running multi-container Docker applications. With Compose, you use a YAML file to configure your application’s services. Then, with a single command, you create and start all the services from your configuration.