ActiveModel is a library which contains various modules which when added to a class add some features present on Active Record to the class. One such module is ActiveModel::Naming module. This module is used for model name introspection .Below are the methods of this module:

class User
  extend ActiveModel::Naming
end

User.model_name.name                # => "User"
User.model_name.singular            # => "user"
User.model_name.plural              # => "users"
User.model_name.element             # => "user"
User.model_name.human               # => "User"
User.model_name.collection          # => "users"
User.model_name.param_key           # => "users"
User.model_name.i18n_key            # => :user
User.model_name.route_key           # => "users"
User.model_name.singular_route_key  # => "user"