How Do Closures Capture Variables in Rust?

Closures in Rust capture variables from their surrounding environment by borrowing or taking ownership of them, depending on how the closure is used. The compiler infers whether to borrow immutably, mutably, or move the variable into the closure's state based on the closure's usage of that variable.

fn main() {
    let x = 5;
    let equal_to_x = |z| z == x; // Captures `x` by immutable borrow
    println!("{}", equal_to_x(5));
}

If the closure needs to modify the captured variable, it captures it by mutable borrow. If the closure needs to own the variable (e.g., to move it to another thread), you must use the move keyword to force ownership transfer.

A closure is a small piece of code that can remember variables from where it was created. It works like a function that carries its own backpack of data, allowing it to access those variables even after the original scope has ended. This is useful for creating custom logic that depends on specific context without passing every variable as an argument.