Heroku runs your apps inside dynos — smart containers on a reliable, fully managed runtime environment.
Developers deploy their code written in Node, Ruby, Java, PHP, Python, Go, Scala, or Clojure to a build system which produces an app that's ready for execution. The system and language stacks are monitored, patched, and upgraded, so it's always ready and up-to-date. The runtime keeps apps running without any manual intervention.