What Are Blocks and Scopes in Rust?

Blocks are code sections enclosed in curly braces {} that define a scope, while scopes determine where variables are accessible and when they are dropped. When a variable's owner goes out of scope at the end of a block, the variable is dropped and its memory is freed.

fn main() {
    let x = 5; // x is valid from here
    {
        let y = 10; // y is valid only inside this block
        println!("y is {y}");
    } // y goes out of scope and is dropped here
    println!("x is {x}"); // x is still valid
    // println!("y is {y}"); // Error: y is out of scope
}

A block is a section of code wrapped in curly braces that creates a temporary workspace for variables. A scope is the specific area where a variable exists; once the code leaves that area, the variable is automatically deleted to free up memory. Think of a block like a meeting room: you can bring your notes (variables) inside, but you must leave them at the door when you walk out.