Your BU student (or employee) ID card is your library card for checking out items at the Cullom-Davis Library. You can also use your BU ID card to check out books at other libraries in the I-Share system. For example, you can go to the ICC Library and check out a book from their collection using your BU ID. You can also request for items to be sent from other libraries to this library for you to check out using the I-Share catalog (See: How do I request an item through I-Share?).
Your ID card cannot be used to check out books from local public libraries.