The version of the documentation you are looking at is 0.10.1.
If you are browsing this online (at ruby-doc.org), then you are looking at the latest version. If you wish to download this for offline viewing, click the following link:
As you browse, whether online or offline, remember that the downloads directory and online documentation are linked from the Web Links box in the table of contents.
When you download a tarball or zipfile, be aware that you can install it. This will copy the documentation to a central directory so your browser bookmarks will remain valid as you install new versions. Installation is optional; you can point your browser to stdlib/index.html wherever you unpack it and all the documentation will be accessible.
Here is an example installation session.
[/tmp/ruby-doc-stdlib-0.8.1] $ ruby install.rb --help Usage: ruby install.rb [options] Options: -d, --doc-base DIR Install documentation to DIR/stdlib -f, --force Don't ask any questions; just install -i, --interactive Confirm any risky actions -h, --help Show this message [/tmp/ruby-doc-stdlib-0.8.1] $ ruby install.rb /usr/local/doc/ruby/stdlib contains the same version you want to install. Shall I bother? [y/N] y Installing stdlib directory to /usr/local/doc/ruby/stdlib You happy to proceed? [y/N] y * copying files to /usr/local/doc/ruby/stdlib.tmp * removing old installation * moving temporary files to /usr/local/doc/ruby/stdlib Successfully installed to /usr/local/doc/ruby/stdlib. Please point your browser to /usr/local/doc/ruby/stdlib/index.html.
The installer takes care of existing installations and asks you before doing anything risky.