Ruby

Early releases

Following the release of Ruby 0.95 in 1995, several stable versions of Ruby were released in the following years:

    Ruby 1.0: December 25, 1996
    Ruby 1.2: December 1998
    Ruby 1.4: August 1999
    Ruby 1.6: September 2000

In 1997, the first article about Ruby was published on the Web. In the same year, Matsumoto was hired by netlab.jp to work on Ruby as a full-time developer.

In 1998, the Ruby Application Archive was launched by Matsumoto, along with a simple English-language homepage for Ruby.

In 1999, the first English language mailing list ruby-talk began, which signaled a growing interest in the language outside Japan. In this same year, Matsumoto and Keiju Ishitsuka wrote the first book on Ruby, The Object-oriented Scripting Language Ruby (オブジェクト指向スクリプト言語 Ruby), which was published in Japan in October 1999. It would be followed in the early 2000s by around 20 books on Ruby published in Japanese.

By 2000, Ruby was more popular than Python in Japan. In September 2000, the first English language book Programming Ruby was printed, which was later freely released to the public, further widening the adoption of Ruby amongst English speakers. In early 2002, the English-language ruby-talk mailing list was receiving more messages than the Japanese-language ruby-list, demonstrating Ruby's increasing popularity in the English-speaking world.
Ruby 1.8

Ruby 1.8 was initially released in August 2003, was stable for a long time, and was retired June 2013. Although deprecated, there is still code based on it. Ruby 1.8 is only partially compatible with Ruby 1.9.

Ruby 1.8 has been the subject of several industry standards. The language specifications for Ruby were developed by the Open Standards Promotion Center of the Information-Technology Promotion Agency (a Japanese government agency) for submission to the Japanese Industrial Standards Committee and then to the International Organization for Standardization. It was accepted as a Japanese Industrial Standard (JIS X 3017) in 2011 and an international standard (ISO/IEC 30170) in 2012.[27]

Around 2005, interest in the Ruby language surged in tandem with Ruby on Rails, a web application framework written in Ruby. Rails is frequently credited with increasing awareness of Ruby.
Ruby 1.9

Ruby 1.9 was released in December 2007. Effective with Ruby 1.9.3, released October 31, 2011, Ruby switched from being dual-licensed under the Ruby License and the GPL to being dual-licensed under the Ruby License and the two-clause BSD license.[30] Adoption of 1.9 was slowed by changes from 1.8 that required many popular third party gems to be rewritten.

Ruby 1.9 introduces many significant changes over the 1.8 series. Examples:

    block local variables (variables that are local to the block in which they are declared)
    an additional lambda syntax: f = ->(a,b) { puts a + b }
    per-string character encodings are supported
    new socket API (IPv6 support)
    require_relative import security

Ruby 2.0

Ruby 2.0 added several new features, including:

    method keyword arguments,
    a new method, Module#prepend, for extending a class,
    a new literal for creating an array of symbols,
    new API for the lazy evaluation of Enumerables, and
    a new convention of using #to_h to convert objects to Hashes.

Ruby 2.0 is intended to be fully backward compatible with Ruby 1.9.3. As of the official 2.0.0 release on February 24, 2013, there were only five known (minor) incompatibilities.
Ruby 2.1

Ruby 2.1.0 was released on Christmas Day in 2013. The release includes speed-ups, bugfixes, and library updates. Starting with 2.1.0, Ruby is using semantic versioning.
Ruby 2.2

Ruby 2.2.0 was released on Christmas Day in 2014. The release includes speed-ups, bugfixes, and library updates and removes some deprecated APIs. Most notably, Ruby 2.2.0 introduces changes to memory handling - an incremental garbage collector, support for garbage collection of symbols and the option to compile directly against jemalloc. It also contains experimental support for using vfork(2) with system() and spawn(), support for Unicode 7.0.

Features now obsolete or removed include callcc, the DL library, Digest::HMAC, lib/rational.rb, lib/complex.rb, GServer, Logger as well as various C API functions.

( Source: Wikipedia )