The purpose of a story is to gather insight and build narratives from your data. You structure the story to convince your audience.
To achieve that, you take snapshots of your visualizations and put them in slides. To make your slides stand out you can apply visual effects, add text and shapes. You can also embed sheets to make your story interactive.
A story is connected to its app, so you can return to the live data anytime, to discover new and hidden stories.