The Heroku Command Line Interface (CLI), formerly known as the Heroku Toolbelt, is a tool for creating and managing Heroku apps from the command line / shell of various operating systems.
This software requires a Heroku account in order to work. Heroku lets you deploy, run and manage applications written in Ruby, Node.js, Java, Python, Clojure, Scala, Go and PHP. An application is a collection of source code written in one of these languages, perhaps a framework, and some dependency description that instructs a build system as to which additional dependencies are needed in order to build and run the application. Dependency mechanisms vary across languages: in Ruby you use a Gemfile, in Python a requirements.txt, in Node.js a package.json, in Java a pom.xml and so on. The source code for your application, together with the dependency file, should provide enough information for the Heroku platform to build your application, to produce something that can be executed.