What is the purpose of the 'derive' attribute in Rust?

In Rust, the `derive` attribute is used to automatically implement common traits for custom data types. It provides a convenient way to generate boilerplate code for traits without explicitly implementing them. The `derive` attribute saves developers from writing repetitive and error-prone code, improving productivity and maintainability.

By applying the `derive` attribute to a struct or an enum, you can automatically derive implementations for traits such as `Debug`, `Clone`, `Copy`, `PartialEq`, `Eq`, and many others. These traits provide useful functionalities and behaviors for the types they are implemented on.

Here's an example that demonstrates the usage of the `derive` attribute:

#[derive(Debug, Clone, PartialEq)]
struct Person {
    name: String,
    age: u32,
}

fn main() {
    let person1 = Person {
        name: String::from("Alice"),
        age: 30,
    };

    let person2 = person1.clone();

    println!("{:?}", person1); // Output: Person { name: "Alice", age: 30 }
    println!("{:?}", person2); // Output: Person { name: "Alice", age: 30 }

    println!("Are they equal? {}", person1 == person2); // Output: true
}​

In this example, the `derive` attribute is applied to the `Person` struct, specifying that the `Debug`, `Clone`, and `PartialEq` traits should be automatically implemented. As a result, we get the ability to print the `Person` struct with `println!` using the `Debug` trait's formatting (`{:?}`), create a clone of the `Person` struct using the `clone()` method, and compare two `Person` structs using the `==` operator.

By using the `derive` attribute, the compiler generates the necessary implementations for the specified traits, saving us from manually implementing them. This makes the code shorter, easier to read, and less error-prone.