juniorRust
What is mutability in Rust?
Updated May 24, 2026
Short answer
Mutability determines whether a variable can be changed after assignment.
Deep explanation
Variables are immutable by default in Rust. The mut keyword explicitly allows modification, improving safety and predictability.
Real-world example
Counters, accumulators, and state updates in applications.
Common mistakes
- Overusing mutability instead of leveraging immutable patterns.
Follow-up questions
- Why are variables immutable by default?
- Can references be mutable?