Postback is a message or value that is passed to ChatBot when a user clicks a button.
Let’s say that you use a Gallery response with more than one card. Each card presents a different product but all of them have the same button title which is View. In such a case, you can add a specific postback message or value to each card to distinguish which button was clicked.
Additionally, postback is treated as a user query, and it can be saved by the entity that follows it. For example, you can add a subsequent interaction with “sys.any” that will save the Blueberry house answer as an attribute.