# Vue3 `createApp()` Function * * Vue3 Global API](#) In Vue3, `createApp()` is a global function used to create a new Vue application instance. `createApp()` is the entry point for a Vue application. All components, plugins, routes, etc., must be registered and configured through this instance. With `createApp()`, you can easily create, configure, and manage a Vue application, and mount it to a DOM element on the page. Unlike `new Vue()` in Vue2, Vue3 introduces `createApp()` to create application instances, making the Vue API more modular and flexible. The function syntax is as follows: function createApp(rootComponent: Component, rootProps?: object): App The first parameter is the root component. The second parameter is optional and represents the props to be passed to the root component. * * * ## Basic Usage of `createApp()` To use `createApp()`, you first need to import it from the Vue library. Here is a simple example: ## Example // From Vue Import the createApp function from the library import{ createApp } from 'vue'; // Create a root component const App ={ template: `

Hello, Vue3!

` }; // Use createApp to create an application instance and mount it to a DOM element const app = createApp(App); app.mount('#app'); In this example, we first imported the `createApp` function from the `vue` library. Then, we defined a simple root component `App` that simply displays a heading on the page. Next, we created a Vue application instance using `createApp(App)` and mounted it to the DOM element with the ID `app` on the page. * * * ## Return Value of `createApp()` The `createApp()` function returns an application instance object, which provides many methods and properties for configuring and managing the Vue application. For example, you can use the `.mount()` method to mount the application to a DOM element, or use `.u