What are plugins in drupal 8 | drupal 9 | drupal 10

What are plugins in Drupal 8 ------------------- Symfony twig tutorial | Twig Template Engine Introduction | in Hindi https://www.youtube.com/watch?v=5r4rGxHS3tM Installing drupal 9 on ddev local | in hindi https://www.youtube.com/watch?v=c0H4Wq2mrqo Introducing DDEV Local Containers | in Hindi https://www.youtube.com/watch?v=czhVZYoZ7CA Services and dependency injection Drupal 8 | Drupal 9 | drupal10 in Hindi https://www.youtube.com/watch?v=7mqsUiwaXuQ Creating a custom form in a block in Drupal 8, Drupal 9 in Hindi https://youtu.be/wMPiCfqhJew Create a Dependent Dropdown with Ajax for Drupal 8, Drupal 9 in Hindi https://www.youtube.com/watch?v=H3YFWaKzf9o&t=241s How to Create a custom block to render data dynamically in twig Drupal8? https://www.youtube.com/watch?v=nSSKMEwEomE Specifying custom permission for a new page in Hindi https://www.youtube.com/watch?v=Pt2I9QH1FjU&t=0s Drupal 8 tutorial for beginners step by step in Hindi https://www.youtube.com/playlist?list=PLI_x5XaZMJqgXvg3lAZwxLi7jpwF-caI4 Drupal 8 Module Development in Hindi https://www.youtube.com/playlist?list=PLI_x5XaZMJqiRx6onlJ60tdol0kD5AmKv Drupal 8 Paragraphs Module Tutorial in Hindi https://www.youtube.com/playlist?list=PLI_x5XaZMJqj1lKNHyecxA3zIkm2SO5KD Building Custom Theme in Drupal (Hindi) https://www.youtube.com/playlist?list=PLI_x5XaZMJqhlItnF1TJU4I6TWFKFhPZQ