Ruby Version Manager
- RVM: which is the most established, but also the most intrusive in terms of shell modifications. It manages gemsets and installs different ruby versions. Most of that functionality has been surpassed by Bundler.
- rbenv: which is lower impact. Does not install ruby versions. It only manages different ruby versions. But it also do things like overriding cd so that it can switch rubies “magically”. They also install shims of commands like gem, ruby, and others that dynamically look up the available Rubies.
- chruby: even lighter than rbenv.