To fully understand what it is, we must begin to explain that Rails is a development tool that gives web developers the possibility of a framework, providing a structure for all the code they generate. The Rails framework helps these people create applications and websites because it takes and simplifies the tasks that are repeated and that are common.
Rails are written in Ruby which is the programming language that is also used together with Rails. If you want some examples, Ruby is for Rails as PHP for Symfony and Zend, or as Python for Django. But what attracts Ruby's developers the most is its elegance and simplicity of language.
Just to get an idea, Ruby on Rails is much more famous than you think, just to cite some of the famous cases, it should be said that Twitter was developed in the beginning with this web framework. GitHub itself is also developed with Ruby on Rails, a mandatory step for the publication of any open source development, also for computers that need to share code. Hulu, BaseCamp, SoundCloud. To this are added many companies and web applications that saw in the framework an excellent way of development.
Before starting to number the main benefits of this tool, we must be honest and also say some of the main problems it presents.
Not all web page hosts support Rails. Although it is true that not all servers support Rails, this usually occurs because more resources are required than PHP, something that discourages low-end shared hosting providers.
Performance and scalability. There are concerns that there are Raid applications that are not as fast as Java or C, and it may be true, but most Apps work fast enough.
Java and PHP are more popular, and there are more developers in these languages. The number of Ruby developers is growing year after year as more people switch to it from other programming languages.
Knowing some of the negatives, now the question to solve is why we should use Ruby on Rails