**Definition:**
Polymorphism is a programming concept that allows objects of different classes to be treated as objects of a common superclass. It enables methods to perform differently based on the object that is calling them.

**Key ideas:**
- Polymorphism can be achieved through method overriding and method overloading.
- It promotes code reusability and flexibility in programming.
- It allows for easier maintenance and scalability of code.
- Polymorphism is a key feature in object-oriented programming languages.

**Why this topic matters in this category:**
Understanding polymorphism is essential for writing efficient and adaptable code in computer programming.