Expressions are the backbone of Qlik Sense applications. We use them in scripts as well as in charts. But expressions would not give you much if it wasn't for the powerful QIX engine. Set analysis sets Qlik Sense apart from other tools on the market. With it, we can achieve beyond powerful analysis throughout our data model.

Variables also help us create dynamic and easier-to-maintain expressions. Use it to store part of your expressions, such as values in your set modifiers or full expressions. Dollar-sign expansion allows you to return the value of a variable.

Use user-defined functions for repetitive tasks. These variables, which are in essence functions, allow you to easily reuse code in new applications. Store your user-defined functions in a centralized file and reuse them when needed!.

In the next chapter, you will learn about Qlik Sense APIs which allow you...