# Polymorphism

URL: https://softwaredictionary.org/terms/polymorphism
Category: Programming Fundamentals
Last updated: 2026-09-30
In Turkish: Çok biçimlilik
Pronunciation: pol-ee-MOR-fiz-um

In short: Polymorphism is the ability of code to work with values of different types through one shared interface, with each type supplying its own behavior.

## What is polymorphism in programming?

Polymorphism, from the Greek for 'many forms', means the same piece of code can work with objects of different types. You call a method such as `area()` on a shape without knowing whether it's a circle or a square, and each object responds in its own correct way. This lets you write general code once and add new types later without changing it.

The most common form in object-oriented programming is subtype polymorphism: classes that share a parent class or interface each override the same method, and at runtime the language picks the right version based on the object's actual type, a process called dynamic dispatch. Method overloading, where one class has several methods with the same name but different parameters, is another form that is resolved at compile time. Generics are a third form, called parametric polymorphism, where one function or class works with many types.

A universal remote is a good analogy: pressing the power button works on the TV, the soundbar, and the streaming box, even though each device turns on in its own way. In the same way, a payment system can call `pay()` on card, bank transfer, or wallet objects alike, and a drawing app can loop over a list of shapes and call `draw()` on each one.

Polymorphism is often confused with inheritance. Inheritance is one way to share code between classes, while polymorphism is the ability to use different types through a common interface, which can also come from interfaces or from duck typing in dynamic languages like Python and JavaScript, where any object with the right method works. A long `if` or `switch` statement that checks an object's type before deciding what to do is a sign that polymorphism would help.

## Key takeaways

- Polymorphism means one interface, many implementations.
- Subtype polymorphism picks the right overridden method at runtime based on the object's actual type.
- Method overloading and generics are other forms of polymorphism.
- Duck typing gives dynamic languages polymorphism without a shared parent class.
- It replaces long type-checking `if` or `switch` chains with a single method call.

## Example: One loop, many shapes in JavaScript

```javascript
class Shape {
  area() { return 0; }
}
class Circle extends Shape {
  constructor(r) { super(); this.r = r; }
  area() { return Math.PI * this.r ** 2; }
}
class Square extends Shape {
  constructor(side) { super(); this.side = side; }
  area() { return this.side ** 2; }
}

// One loop works for every kind of shape, including ones added later
const shapes = [new Circle(1), new Square(2)];
for (const s of shapes) console.log(s.area()); // 3.14159..., then 4
```

## Frequently asked questions

**What is the difference between polymorphism and inheritance?**

Inheritance lets a class reuse and extend another class's code, while polymorphism lets code treat objects of different types through a shared interface. Inheritance is one common way to get polymorphism, but interfaces and duck typing achieve it without sharing any code.

**What is the difference between overloading and overriding?**

Overloading means several methods in the same class share a name but take different parameters, and the compiler picks one at compile time. Overriding means a subclass replaces a parent's method that has the same signature, and the right version is picked at runtime.

**What are the types of polymorphism?**

The main types are subtype polymorphism (overriding methods from a shared parent or interface), ad hoc polymorphism (method and operator overloading), and parametric polymorphism (generics). Dynamic languages also rely heavily on duck typing.

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Software Dictionary: https://softwaredictionary.org/ · https://softwaredictionary.org/llms.txt