This diagram shows a Thing class which has a name and a description (in a Ruby program, these might be internal variables such as @name and @description plus some methods to access them). The Treasure and Room classes both descend from the Thing class so they auto-matically ‘inherit’ a name and a description. The Treasure class adds one new item: value – so it now has name, description and value; The Room class adds exits – so it has name, description and exits.