module ActionController::StrongParameters

def params

has been instantiated with the request.parameters.
Returns a new ActionController::Parameters object that 
def params
  @_params ||= begin
    context = {
      controller: self.class.name,
      action: action_name,
      request: request,
      params: request.filtered_parameters
    }
    Parameters.new(request.parameters, context)
  end
end

def params=(value)

object that has been instantiated with the given +value+ hash.
is a Hash, this will create an ActionController::Parameters
Assigns the given +value+ to the +params+ hash. If +value+ 
def params=(value)
  @_params = value.is_a?(Hash) ? Parameters.new(value) : value
end