Since starting to use Power BI I have been advocating the following 'basic' model

However. You can also create reports within Power BI Service. This is mentioned within the certification route for DA 100 Analysing Data with Power BI. Which makes things a little more confusing and I have been asked on lots of occasions. "If you can do everything in Service, what is the point of using Desktop?"
This post will hopefully answer that question.
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