Business intelligence/business analytics is in high demand. Companies are constantly searching for ways to make better and faster and smarter decisions. Therefore, they rely heavily on data. Small company or multinational - data-driven decision making is the key to success for any business in the world of tomorrow. Because of this, companies are drastically increasing to step up their efforts to find skilled employees and freelancers with the necessary capabilities to help with analyzing data and creating valuable highly profitable insights. Therefore, Power BI as the leading BI tool from Microsoft is in remarkably high demand. When we want to do calculations in Power BI, we need DAX (Data Analysis Expressions). Here, we explore all the DAX fundamental key concepts. You will start with looking at row context, followed by iterators. After that, you will look at filter context and context transition. Finally, you learn about the expanded tables. By the end of this course, you will learn the fundamental key concepts of DAX in Power BI to do your data analysis work. You can repeat the concepts from time-to-time and master your DAX journey. All the resource files are uploaded on the GitHub repository at https://github.com/PacktPublishing/Mastering-the-Power-BI-Key-Fundamentals