Shows example of usage of Magento 2 emulate area code

m2-php-emulate-area-code.php

<?php
declare(strict_types=1);

namespace Vendor\Module\Service;

use Magento\Framework\App\Area as AppArea;
use Magento\Framework\App\State as AppState;
use Magento\Framework\DataObject;
use Magento\Framework\Exception\NoSuchEntityException;

/**
 * Class SetCategoriesNavigationSettingsService
 */
class SetCategoriesNavigationSettingsService
{
    /**
     * @var AppState
     */
    private $appState;

    /**
     * @var UpdateCategoryService
     */
    private $updateCategoryService;

    /**
     * Class constructor
     *
     * @param AppState $appState
     * @param UpdateCategoryService $updateCategoryService
     */
    public function __construct(
        AppState $appState,
        UpdateCategoryService $updateCategoryService
    ) {
        $this->appState = $appState;
    }

    /**
     * Example on how to emulate area and pass some method as callback
     *
     * @return void
     */
    public function execute(): void
    {
        // Method #1 to call some other stuff
        $this->appState->emulateAreaCode(
           AppArea::AREA_ADMINHTML,
           [$this->updateCategoryService, 'execute'],
           [$param1, $param2]
        );

        // Method #2 to call some other stuff
        $categoryId = 100;
        $service = $this->updateCategoryService;

        $this->appState->emulateAreaCode(
            AppArea::AREA_ADMINHTML,
            function() use ($service, $categoryId) {
                $service->execute($categoryId);
            }
        );
    }
}

Thank you kindly for your example. Would you also care to explain when and why to emulate an area? That is still unclear to me.