If you're interested in using RVM to manage multiple versions of Ruby on your system I wanted to give some more detailed instructions on how you can accomplish this. Start out by going to your terminal and typing the command:

rvm list

If you have RVM installed this will bring up all of the versions of Ruby that you have access to on your computer. If there is a version of Ruby that you want and that you don't already have on your system, simply type this into the terminal:

rvm install 2.3.0

Running this command will install the 2.3.0 version of Ruby for you.

You can do this for any versions of Ruby that are available via RVM. This makes it easy to ensure you're always using the most up to date version of the language. Using RVM is also helpful if you have different projects that utilize various versions of the language. For example, I have some legacy Ruby projects that use Ruby version 1.9.3, while all of my new projects use Ruby 2.3.0 (at the time of writing this guide).

By leveraging RVM I can quickly switch between different versions of Ruby with a simple terminal command. Alternatively if you're not a fan of RVM you can also use rbenv, which is a similar service.