Within the Power BI interface, there are three main tabs. We have the Reports tab, the Data tab, and the Model tab. The reports tab is the default, and it's where you see the canvas. This is the main place where visualizations are created and arranged, and it's where we've been working so far in this course, but the other tabs are very important and we will be spending plenty of time on those in this course as well.

All right. So next in line is the Data tab. Data View allows you to see all of the tables in your data sources, and they're all listed on the right-hand side. This is where we validate data, mine and transform data, create data we need if it doesn't already exist, and check data types. So I'm checking this data type right here, and it's a good thing we checked because this should be a number format, not text, which is very important in Power BI. This last tab is the Model tab, and this allows you to create and manage relationships between tables.

Relationships are a very important concept. They allow us to use the data from two or even more tables in the same visual. A relationship is where two or more tables are linked together because they each have a specific column of data in common. Think of store IDs. We have this store's table with a bunch of information about stores, and it has their store IDs listed in one of the columns. We have this other table, which is a list of all of the sales transactions that have happened at our company, and we make sure to record which store they happened at. So this table also has the store IDs. We can create a relationship between these tables using their matching information, the store IDs. And now we're able to perform analyses we would not previously have been able to perform, such as seeing a list of all of our stores by store description, and what each one of their total sales is.