A timeline of events is presented as a scrollytelling story, where text steps on the left trigger an embedded Flourish story on the right. The example uses the Scrollama library and D3.js to manage the scroll-driven navigation. The Flourish iframe is advanced through its embed API based on the active step, while D3 handles element selection for Scrollama's configuration. The data source is the embedded Flourish story, with the timeline's specifics not defined in this code.