What does immutable mean?

The term "immutable" refers to the property of data that cannot be changed or modified after it has been created. In programming, particularly in languages like Python, this means that once an immutable object is assigned a value, that value remains constant and cannot be altered. Common examples of immutable types in Python include tuples and strings.

When an immutable object is manipulated, instead of modifying the original object, a new object is created with the altered value. This characteristic is crucial for ensuring data integrity and avoiding unintended side effects when the same data is used across different parts of a program. Understanding immutability is essential for managing memory and optimizing performance.

The other options do not align with the definition of immutability. Data that can be freely updated would imply it is mutable, while data that is temporary or accessible to all does not speak to the ability to modify the data. Thus, recognizing that immutability strictly restricts modification reinforces the understanding of how certain data types behave within programming languages.