Accidental properties refer to characteristics of an object or entity that are not essential to its identity. For example, the color of a car is an accidental property; a red car can be painted blue without changing its fundamental nature as a car. These properties can change without altering what the object fundamentally is. In contrast, essential properties are those that define the object's core identity. For instance, being a mammal is an essential property of a dog. Accidental properties can vary widely, such as the height of a building or the age of a person, but they do not affect the object's classification.