In Drupal 7, blocks used hook_block_info() and then a number of block hooks beyond that.

When block info was replaced by the block plugin type in Drupal 8, all of those block hooks became methods of the plugins, representing each block.

To overcome this, an abstract block class was built that provides same defaults for all of the core provided blocks and their methods. Thus, the block plugins only overrides the methods they specifically need to provide for.

So Basically, The Drupal 8 plugin system provides a set of guidelines and reusable code components to allow developers to expose pluggable components within their code and (as needed) support managing these components through the user interface.

In our talk, We're going to cover the following topics:

• What are plugins?
• What are plugin types?
• What are Annotations and how are they related?
• Defining a plugin
• Complete overview of the plugin system

Key Takeaways from this talk:

• For anyone who is willing to write plugins and where they fit inside the architecture.
• Understand the difference b/w Drupal 7 vs Drupal 8 plugin system.