The Magento 2 helper is the class which is used for adding functionalities to several features and can be used anywhere in the entire website. They are created as Singleton (single instances of objects) which can be called in controllers, views, models, templates etc.

Create Magento 2 Custom Module <br>
Add **module.xml** file in `app/code/Magenticians/Mymodule/etc` and copy the following code in it:

    <?xml version="1.0"?>
                <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
                            <module name="Magenticians_Mymodule" setup_version="1.0.1">
                            </module>
                </config>


Add **registration.php** in `app/code/Magenticians/Mymodule` and copy the following code in it:

    <?php
    \Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,
    'Magenticians_Mymodule',
    __DIR__
    );

Create Magento 2 Helper
Now add **Data.php** file in `app/code/Magenticians/Mymodule/Helper` and copy the following code in it:

    <?php
    
    namespace Magenticians\Mymodule\Helper;
    
    use Magento\Framework\App\Helper\AbstractHelper;
    
    class Data extends AbstractHelper
    {
        /**
         * @var \Magento\Framework\App\Http\Context
         */
        private $httpContext;
    
        public function __construct(
            \Magento\Framework\App\Helper\Context $context,
            \Magento\Framework\App\Http\Context $httpContext
        ) 
        {
            parent::__construct($context);
            $this->httpContext = $httpContext;
        }
    
        public function isLoggedIn()
        {
            $isLoggedIn = $this->httpContext->getValue(\Magento\Customer\Model\Context::CONTEXT_AUTH);
            return $isLoggedIn;
        }
    }

and **observer** file how to helper class call 

    <?php
    
    namespace Magenticians\Mymodule\Observer;
    
    use Magento\Framework\Event\ObserverInterface;
    
    class Mymodulename implements ObserverInterface
    {
        ...
    
        protected $dataHelper;
    
        ...
    
        public function __construct(
            ...
            \Magenticians\Mymodule\Helper\Data $dataHelper
            ...
        ) {
            ...
            $this->dataHelper = $dataHelper;
            ...
        }
    
        public function ...(){
            $helper = $this->dataHelper->isLoggedIn();
        }
    
        ...
    }
    
    ?>