Pulled from the source code using RDoc, this reference work documents the standard library. The Ruby Standard Library Documentation collection, brought to you by the Ruby-doc project. Whether you are browsing online or offline, we hope that your use of Ruby’s standard library will become more productive as a result of this effort.
Ruby-doc is a project dedicated to creating and collecting documentation on Ruby. You can find collections of articles and other resources at the website. stdlib-doc is a RubyForge project that converts Ruby source code into this documentation you are looking at. It also tracks the status of the documentation effort; you can see some of that effort in the Status Report page.
Link: Read online.