2. Difference between interface and implementation

• What user needs to know about functionality built into our object?

  • Ideally, user needs a set of operations, supported by each object.

  • However, the user does not care how each operation is implemented.

• For example, a browser program can have

  • a list of bookmarks (favorites)...

  • ...but every browser will do different things to navigate when a user clicks bookmarked item.