Specify the kinds of objects to create using a prototypical instance, and create new objects by copying this prototype. Pattern has creational purpose and deals with object relationships, which are more dynamic. The pattern hides the complexities of making new instances from the client.

• when the classes to instantiate are specified at run-time
• to avoid building a class hierarchy of factories that parallels the class hierarchy of products
• when instances of a class can have one of only a few different combinations of state