Immutability
Noun · Development
Definitions
The property of data that cannot be changed after creation. Instead of modifying existing values, operations produce new values. Eliminates entire classes of bugs related to shared mutable state and is fundamental to functional programming and concurrent systems.
In plain English: The idea that data should never be changed after it's created — instead, you make new copies with the changes you want. Prevents a lot of subtle bugs.
Example: "Once we made our state immutable, the race conditions disappeared and debugging became straightforward."