Broadcast messages can be used for many purposes. Here are several examples of different uses for broadcast messages.
Sending out sale notices.
Alerting subscribers of a new blog post.
Notifying subscribers of an upcoming podcast.
Letting subscribers know about an event that you will be putting on.
Sending out links to a news report.
You can use broadcast messages in so many ways. Just think and brainstorm all the uses you can use broadcast messages to convey information to your subscribers.