Adaptive Cards are platform-agnostic snippets of UI, authored in JSON, that apps and services can openly exchange. When delivered to a specific app, the JSON is transformed into native UI that automatically adapts to its surroundings. It helps design and integrate light-weight UI for all major platforms and frameworks.
In other words, the card can contain UI elements to all for buttons, input etc. In the case of the FTS App, the adaptive card is used to display the headline and summary of an article and will give they user the ability to launch the article for reading or the FTS App so that the user can see and manipulate the tags, and other capabilities available from the application.
One of the nice aspects of the adaptive card is that it will work when an article is shared from within the FTS App or when a URL is pasted into a chat directly.
The URL unfurling also works when a channel URL or Dashboard URL is shared.