fn main() {
    println!("Hello, world!");
}

Run the program:

cargo run

This is the normal Rust entry point. println! is a macro that writes formatted output to the terminal.

Variables are immutable by default. Use mut when the value should change.

let language = "Rust";
let mut count = 1;
count += 1;

Rust values are immutable unless you mark them with mut, which makes state changes explicit.

Values have a single owner. Borrow with references when a function should read data without taking ownership.

fn main() {
    let name = String::from("Dan");
    greet(&name);
    println!("{}", name);
}

fn greet(name: &str) {
    println!("Hello, {name}");
}

This shows borrowing with &name, so the function can read the value without taking it away from the caller.