Creating and nesting components React apps are made out of components. A component is a piece of the UI (user interface) that has its own logic and appearance. A component can be as small as a button, or as large as an entire page.
React components are JavaScript functions that return markup:
function MyButton() { return ( I'm a button ); } Now that you’ve declared MyButton, you can nest it into another component:
export default function MyApp() { return (
); } Notice that starts with a capital letter. That’s how you know it’s a React component. React component names must always start with a capital letter, while HTML tags must be lowercase.