Ruby on Rails 4.2 recently released, is an open-source web framework that’s optimized for programmer happiness and sustainable productivity. It lets you write beautiful code by favoring convention over configuration. This release is probably the most well-tested new major release of Rails in a long time. Through four betas and three release candidates, tons of people have helped ensure that regressions and bugs have been caught. Since the first beta, there have been some 1600+ commits of spit and polish applied.