<< include >>

• A way of simplifying a use-case by separating it's functionality in another use case.
• For example-both withdraw money and deposit money use-case require the customer to login.
• The << include >>association specifies that to accomplish the use-case withdraw money,the user must login to the account.

<< extend >>

• Used to extend the behaviour of a base use case.
• You can add the extend relationship to a model to show the following situations.
  • A part of the use-case that is optional behaviour