What do you activate when you want to add applications or functionality within your development instance?

An 'App Package' is not the standard ServiceNow terminology for adding functionality; applications are typically delivered and enabled via plugins.

'Updated Pack' is not a standard ServiceNow term for adding new applications or functionality; updates are typically delivered via patches or family releases.

A patch is a collection of fixes and minor enhancements applied to an existing version of ServiceNow, not a mechanism to add entirely new applications or features.

Plugins are software components that provide additional features and functionality to a ServiceNow instance, and they must be activated to extend the platform's capabilities with new applications or modules.

'App Updated Set' is not standard terminology; Update Sets are used to move configuration changes between instances, not to activate new applications or features within an instance.