Newbie, can not find irb

Hello,

Just installed ruby to start learning it. Running it on RHEL 6.6,
installed it with yum install ruby.

These are the packages it installed:
rpm -qa | grep ruby
ruby-libs-1.8.7.374-3.el6_6.x86_64
ruby-1.8.7.374-3.el6_6.x86_64

The irb command isn’t found on my system:
irb
-bash: irb: command not found

find / -name irb #returns nothing

Am I missing some packages?

I did successfully and execute a hello, world ruby script.

Thank you!