When a class has a dependent class, but the class itself is not dependent on its own dependent class, the relationship between those classes is called a dependency relationship. In a dependency relationship, any change in the dependent class doesn't have any effect on the class it is dependent on. But the dependent class will be affected if the class that it is dependent on changes.

This relationship is represented by a dashed line with an arrow at the end. For example, let's imagine that we have a theme on our mobile phone. If we change the theme, the phone's icons will change, so the icons have a dependency on the theme. This relationship is shown in the following diagram: