Tangents are paths within a convo that allow the customers to choose their direction through the experience. For example, if you are writing a convo about making salsa, you may give the customer the option to learn about making mild salsa or spicy salsa. You would create one tangent for spicy salsa and one for mild salsa.
In the photo above, you will get a different answer depending on which button you click. That experience is created using tangets.