What is the Impl keyword in Rust?

struct Person {
  name: String,
  age: u32
}
// Implementing functionality on the Person struct with the impl keyword
impl Person{
  // This method is used to introduce a person
  fn introduction(&self){
    println!("Hello! My name is {} and I am {} years old.", self.name, self.age);
  }
  // This method updates the age of the person on their birthday
  fn birthday(&mut self){
    self.age = self.age + 1
  }
}
fn main() {
  // Instantiating a mutable Person object
  let mut person = Person{name: "Hania".to_string(), age: 23};
  
  // person introduces themself before their birthday
  println!("Introduction before birthday:");
  person.introduction();
  
  // person ages one year on their birthday
  person.birthday();
  
  // person introduces themself after their birthday
  println!("\nIntroduction after birthday:");
  person.introduction();
}