Working with Symfony 3-4 components? Which components have you used?

In Symfony 3-4, the following components were frequently used:

• HttpFoundation — for working with HTTP requests and responses.
• Routing — for defining routes and linking URLs to controllers.
• DependencyInjection — for managing dependencies and services.
• EventDispatcher — for implementing event-driven architecture.
• Security — for authentication and authorization.
• Twig — a templating engine for generating HTML.
• Form — for creating and processing forms.

Working with components usually involves configuring them and integrating them into the application. For example, using DependencyInjection, you can create services and inject them into controllers:

// services.yml
services:
    app.mailer:
        class: App\Service\Mailer
        arguments: ['@mailer.transport']

// In the controller
public function sendEmail(Mailer $mailer) {
    $mailer->send(...);
}

The EventDispatcher was also frequently used for subscribing to events and extending functionality without modifying the core of the application.