what is the use of a case component event in Salesforce lightning?

Hi ,

Here’s a simple use case of using a component event to update an attribute in another component.

• A user clicks a button in the notifier component, ceNotifier.cmp.
• The client-side controller for ceNotifier.cmp sets a message in a component event and fires the event.
• The handler component, ceHandler.cmp, contains the notifier component, and handles the fired event.
• The client-side controller for ceHandler.cmp sets an attribute in ceHandler.cmp based on the data sent in the event.

for more detail you can refer https://developer.salesforce.com/docs/atlas.en-us.lightning.meta/lightning/events_component_example.htm