## Introduction

Charts are the most important area of QlikView because they are the main method of information delivery, and QlikView is all about information delivery.

There are a few terms that I want to just define before we get cracking, just to make sure you know what I am talking about.

The basis of every chart is some kind of calculation—you add up some numbers or you count something. In QlikView, these calculations are called **expressions**. Every chart should have at least one expression. In fact, some charts require more than one expression.

Most of the time, the expression value that is calculated is not presented in isolation. The calculation is normally made for each of the values in a category. This category is generally the values within a field of data, for example, country or month, in the QlikView data model, but it could be a more complex calculated value. Either way, in QlikView charts, this category is called a **dimension**. Some charts, such as a gauge, would normally never have any dimension. Other charts, such as a pivot table, will often have more than one dimension.

Many simple charts will have just one dimension and one expression. For historical and mathematical reasons, the dimension is sometimes called the
**X-Axis** and the expression is sometimes called the
**Y-Axis** and you may see these terms used in QlikView.