The Rack Gem

So far, we’ve only talked about the Rack specification. But there’s also a gem called Rack. You can find the source code for it on Github, read the documentation on Rubydoc, and install it like any other Ruby gem.

$ gem install rack

Why do we need the Rack gem if the rack-compliant web servers and frameworks can communicate without it?

There are a few important reasons. Let's explore them one-by-one.