Passing data through as prop

App.vue

<template>
  <div id="app">
    <img alt="Vue logo" src="./assets/logo.png">
    <HelloWorld :msg="message"/>
  </div>
</template>

<script>
import HelloWorld from './components/HelloWorld.vue'

export default {
  name: 'app',
  components: {
    HelloWorld
  },
  data(){
    return {
      message: 'Hello World!'
    }
  }
}
</script>

// styles omitted