Following code was tested with ruby 1.9.3 . All objects have to_s method to_s method is define in Object class and hence all ruby objects have method to_s. Certain methods always call to_s method. For example when we do string interpolation then to_s method is called. puts invokes to_s method too. 1class Lab 2 def to_s 3 'to_s' 4 end 5 def to_str 6 'to_str' 7 end 8end 9 10l = Lab.new 11puts "#{l}"