One key feature of the nopCommerce is its pluggable modular/layered architecture which allows additional functionality and presentation elements to be dynamically added to the application at runtime. This pluggable modularized architecture makes it easy to create and manage your nopCommerce based store site.
You can learn more about nopCommerce plugins (including plugin development) here:
Beginner's Guide to nopCommerce Plugin Development - Part 1
Beginner's Guide to nopCommerce Plugin Development - Part 2