Gemified in 2.2-

The following libraries were made standard gems with Ruby 2.2.0 or earlier.

New Default Gems

New Default Gem Description Resources
bigdecimal c Support for arbitrary-precision floating point decimal arithmetic RubyGems · GitHub · RDoc · CRuby · JRuby (1) · JRuby (2) · JRuby (3)
io-console c Patches IO for simple and portable access to the console RubyGems · GitHub · RDoc · CRuby
psych c Support for YAML (YAML Ain't Markup Language) RubyGems · GitHub · RDoc · CRuby
rdoc Ruby documentation generator RubyGems · GitHub · RDoc · CRuby (1) · CRuby (2)
rubygems RubyGems allows you to download, install, and use Ruby software packages on your system RubyGems · GitHub · RDoc · CRuby (1) · CRuby (2) · JRuby (1)

New Bundled Gems

New Bundled Gem Description Resources
minitest Test/spec framework, comes with mocking and benchmark capabilities RubyGems · GitHub · RDoc
power_assert Debug tool that displays intermediate results of a method chain RubyGems · GitHub · RDoc
test-unit A xUnit family unit testing framework (compatibility layer for minitest) RubyGems · GitHub · RDoc

More Standard Gems