A class is declared using the class keyword followed by the class name:

class Person

As in the preceding example, a class in Kotlin need not have a body. Though this is charming, almost all the time you will want your class to have characteristics and behaviors placed within a body. This can be done with the use of opening and closing brackets:

class HelloPrinter {
  fun printHello() {
    println("Hello!")
  }
}

In the preceding code snippet, we have a class named HelloPrinter with a single function declared in it. A function that is declared within a class is called a method. Methods can also be referred to as behaviors. Once a method is declared, it can be used by all instances of the class.