1e41f4b71Sopenharmony_ci# Common Event Subscription Overview 2e41f4b71Sopenharmony_ci 3e41f4b71Sopenharmony_ciThe common event service provides two subscription modes: dynamic and static. The biggest difference between these two modes is that dynamic subscription requires the application to be running, while static subscription does not. 4e41f4b71Sopenharmony_ci 5e41f4b71Sopenharmony_ci- In dynamic subscription mode, a subscriber subscribes to common events by calling an API during the running period. For details, see [Subscribing to Common Events in Dynamic Mode](common-event-subscription.md). 6e41f4b71Sopenharmony_ci 7e41f4b71Sopenharmony_ci- In static subscription mode, a subscriber subscribes to common events by configuring a declaration file and implementing a class that inherits from **StaticSubscriberExtensionAbility**. For details, see [Subscribing to Common Events in Static Mode](common-event-static-subscription.md). 8