Good! Subclassing React.Component is the way to declare a new component class.

When you declare a new component class, you need to give that component class a name. On our finished component, our component class’s name was MyComponentClass:

class MyComponentClass extends React.Component {
  render() {
    return <h1>Hello world</h1>;
  }
}

Component class variable names must begin with capital letters!

This adheres to JavaScript’s class syntax. This naming convention is also seen in other languages that write class names in UpperCamelCase, like Java.

In addition, there is a React-specific reason why component class names must always be capitalized. We’ll get to that soon!