Puma is a web server that can be used in Rails Production and Development environments. It is the default server for Rails 5, but if you’re using an earlier version, it needs to be installed. Although the regular Rails server works fine, Puma is recommended if you’re going to be deploying your app to Heroku.
From development to production – best known as another phase in the app designing process for your perfectly fine development code to error out and blow up on you. Deploying to Heroku is supposed to make this easier. Most of the time this is true, sometimes though, it’s just not. Here is a simple guide for deploying a Rails app to Heroku.