What symbol is used in UML to represent inheritance?

In UML, inheritance is represented by an unfilled triangle, which indicates a generalization relationship between classes. When one class inherits from another, the unfilled triangle points toward the base or parent class. This visualization helps to illustrate the hierarchical structure of classes in object-oriented design, where the subclass derives from the superclass and inherits its properties and behaviors.

The unfilled triangle is distinct in its representation, making it easy to identify relationships at a glance. It emphasizes the direction of the inheritance, allowing viewers to quickly understand which class is the more general or parent class and which is the specialized child class. Other geometric shapes, such as squares, circles, or filled triangles, serve different purposes in UML diagrams, but they do not convey the concept of inheritance in the same clear and established manner as the unfilled triangle does.