What fields of technology use Ruby, and why?

It is used in a wide range of fields, but is best known as a language for Web Applications, because of the Ruby on Rails framework. The general purpose nature of Ruby makes it suitable for a wide array of programming tasks, just like Perl, Python and other general purpose languages. read more

In general I think that ruby and rails are mature technologies capables to build great software, and the only reason you shouldn't use it as your base technologies is because you will use extensive and complex calculations that will require concurrency, to be honest most of the business don't need a high efficiency language but the one who enables their developers to deliver fast, which is the main feature in ruby and rails. read more