Marco Russo and Alberto Ferrari show us how to use variables in DAX:
Variables were introduced in DAX in 2015 and so far, they have proven to be the best enhancement of the DAX language ever. When presented with the concept of variables, most newbies focus on performance improvement, thinking that you introduce variables in your code mainly to obtain better performance. Although variables can improve performance, performance is a minor advantage. There are several more important considerations that should encourage any DAX developer to make extensive use of variables. In this article we share a few considerations, along with best practices about variables and DAX.
Read on to see what makes variables so powerful.