What Is a Move in Rust and When Does It Happen?

A move in Rust transfers ownership of a value from one variable to another, invalidating the original variable. This happens automatically when you pass non-Copy types (like String) to functions or assign them to new variables.

fn main() {
    let s1 = String::from("hello");
    let s2 = s1; // s1 is moved into s2; s1 is no longer valid
    // println!("{s1}"); // Error: borrow of moved value
    println!("{s2}"); // Valid
}

Simple types like i32 implement the Copy trait, so they are duplicated instead of moved.

A move is like handing a physical object to someone else; once you give it away, you no longer have it. In Rust, this prevents two variables from trying to delete the same data at the same time. You only need to worry about this with complex data like text strings, not simple numbers.