form表单post请求保护隐藏秘钥

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
    <form action="/laravel/public/insert" method="post">
        用户名：<input type="text" name="username"><br>
        密码：<input type="password" name="password"><br>
        <button>点击提交</button>
        {{csrf_field()}}
    </form>
</body>
</html>

{{csrf_field()}}

Laravel表单post提交保护