# Understand Contex

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#### Understand Context

How context affects DAX measures is a difficult concept to comprehend. The ensuing visuals will demonstrate how context affects DAX measures so you can see how they interact together.

With Power BI, even though the measure was only defined once, it can be used in these visuals in different ways. Each of the totals is accurate and performs quickly. It is the context of how the DAX measure is used that calculates these totals accurately.

Interactions between visuals will also change how the DAX measure is calculated. For instance, if you select the second visual and then select 2015, the results appear as shown in the following screenshot.

The definition of the DAX measure has not changed; it’s still the original, as shown in the following example:

Total Sales = sum('Sales OrderDetails'[Total Price])