Over time, modules update their shipped configuration such as rules, views, node types. Users expect to get these updates when they update the modules. For example, Drupal Commerce 1.x provides over eleven default views and rules. From release to release, these Views and Rules were enhanced with new features or bug fixes reported by the community.
Take the order management view. In a future release of Drupal Commerce, we may add a newly exposed filter to the view. In Drupal 7 the view would automatically be updated unless it was overridden. That is not the case in Drupal 8.
Drupal 8 introduces the Configuration Management system. While robust, it changes how we work with the configuration in comparison to Drupal 7. Instead of a module owning configuration, configuration is now owned by the site. When a module is installed, its configuration is imported. On module update, no configuration updates are performed. Instead, the module must write an update hook to perform one of the following updates: