Which of these come from Ruby and which from Rails?
• 'person'.pluralize
• 3.days.ago
• params.permit(:name)
• [1,2,3].second
• before_action :authenticate
None of them are Ruby. Every single one is Rails.
I wrote a complete reference of everything Rails adds on top of Ruby — 9 sections, no ActiveRecord, no external gems.

Ruby on Rails — Complete Reference of Methods, Classes & Features Not in Ruby
Ruby on Rails — Complete Reference of Methods, Classes & Features Not in Ruby March 17, 2026 Rails is much more than a framework on top of Ruby — it adds hundreds of methods, classes, and abstr…






