The best example is probably channels. The framework doesn't really have to provide you anything for you to be able to use concurrency. For a personal example, I was able to use RethinkDB changefeeds easily with channels: https://github.com/bbhoss/elixir_friends/blob/master/web/cha...

I just start another process when you join a channel, and that process sets up the changefeed and pushes changes to the client in the form of HTML, allowing messages to be received and processed by the channel. You can watch the full presentation here: https://www.youtube.com/watch?v=aWaleoYD1Ro Slides: http://www.slideshare.net/bbhoss/otp-phoenix-channels-rethin...

Another example is sending email. In Rails, you need to have something like Sidekiq (or now Activejob) to be able to background the job so it doesn't block the response to the client. In Phoenix, you can simply spawn a process to do the work and move on. Sure, you might want a system like exq to keep track of things a bit better, but ultimately the concurrency primitives provides by Erlang/Elixir allow you to do everything you need.