react中什么叫子组件

import React, {Component} from "react";
import { Button } from "antd";
//父组件
export default class Parent extends Component {
    render() {
        return(
            <div>
　　　　　　　　　 <p>这是父组件</p>
                <Child triggerRef={this.bindRef} />
                <Button type="primary" onClick={this.btnClick} >click</Button>
            </div>
        )
    }
    bindRef = ref => { this.child = ref }
    btnClick = () => {
        this.child.getValuefromChild()
    }
}
//子组件
class Child extends Component {
    componentDidMount(){
        this.props.triggerRef(this)
    }
　　//这是子组件的方法
    getValuefromChild = () => console.log("this is child value.")
    render() {
        return <div>这是子组件</div>
    }
}