parent::boot();怎么理解

<?php

namespace App\Models;
.
.
.
use Illuminate\Support\Str;

class User extends Authenticatable
{
    .
    .
    .
    protected $hidden = [
        'password', 'remember_token',
    ];

    public static function boot()
    {
        parent::boot();

        static::creating(function ($user) {
            $user->activation_token = Str::random(10);
        });
    }
    .
    .
    .
}