What is binding and how we can bind different data set

Building dashboard in Wave instead of doing best practice is limiting the usage of multiple data sets. One of the main reasons for this is that the natural faceting that makes widgets interact with each other , you would have to add selection binding in the dashboard JSON in order to make sure that selections worked across data sets and thereby widgets.
We are using two data sets; one with opportunities and one with cases. A list selector with industry and one for Year-Month as well as a date selector. Obviously, you wouldn t in your dashboard have two ways of selecting dates. However, I ve seen both used and they can cause a little trouble, which is why I have added them.