Rust: What is the difference between mut and const in Rust?

mut — mutable variable. const — constant.

mut:

• Mutable variable.
• Can change value.
• Runtime value.
• Default is immutable.

1let mut x = 5;
2x = 10;  // OK

const:

• Constant.
• Cannot change.
• Compile-time value.
• Must have type annotation.

1const MAX_POINTS: u32 = 100_000;
2// MAX_POINTS = 200_000;  // Error!

Key differences:

• mut — mutable, runtime.
• const — constant, compile-time.
• mut — can change.
• const — cannot change.