Imagine the following scenario: You have migrated a report from an old system to the great Power BI and a tester reports a bug in the new report. But the tester does not describe the exact cause, they just export a CSV file from both systems and say that the numbers are not the same. And it is your task to find out what the problem is and, of course, you have to fix it. The first step is to uncover the differences. Earlier, I used Notepad++ or Visual Studio Code for comparing CSV files but nowadays I use Power Query for that!