In plain words
Power BI is Microsoft’s tool for turning rows of data into charts and numbers people can understand. You point it at your data, tidy it up, link the tables together and drag visuals onto a page. People can then click on the charts to explore the data themselves.
Think of a restaurant. The raw data is the vegetables delivered in the morning. Power Query is the prep kitchen where you wash and chop. The model is the recipe that says how things combine. The report is the plate that reaches the customer. The Power BI service is the dining room where people come to eat.
Why it matters
Most organisations already collect plenty of data. The problem is that it sits in spreadsheets, databases and apps that nobody looks at together. Managers ask the same questions every week and someone rebuilds the same Excel chart by hand.
Power BI fixes this. You build the report once. It refreshes on a schedule, so the numbers stay current. Everyone looks at the same figures, and they can filter by campus, month or team without asking for a new chart. At the Campus Help Desk, this means the head of IT can see open tickets by campus every morning without waiting for an email.
How it works
1. Three places you use Power BI.
| Part | What it is | Main job |
|---|---|---|
| Power BI Desktop | A free app for Windows | Build: get data, transform, model, design report pages |
| Power BI service | The website at app.powerbi.com | Share: workspaces, dashboards, apps, refresh, security |
| Power BI mobile apps | Apps for phones and tablets | View reports and dashboards on the move |
Desktop runs only on Windows. If you use a Mac, you need a Windows virtual machine or a cloud PC. The service can do some editing in the browser, but Desktop is the full authoring tool and the one the exam assumes.
2. The flow. Almost every Power BI project follows six steps:
- Get data from files, databases, online services or Dataverse.
- Transform it in Power Query: fix types, clean text, remove what you do not need.
- Model it: create relationships between tables and write measures in DAX, Power BI’s formula language.
- Visualize it: build report pages with charts, cards, tables and slicers.
- Publish the file from Desktop to a workspace in the service.
- Share it through workspace access, an app, links or embedding.
This track follows the same order. Lessons B.3 to B.5 cover getting and transforming data, B.6 to B.10 cover modelling, B.11 to B.13 cover visuals, and B.14 to B.15 cover the service.
3. The main items.
| Item | What it holds | Where it is made |
|---|---|---|
| Semantic model | Tables, relationships, measures and security roles. It used to be called a dataset. | Desktop, then published to the service |
| Report | One or more pages of interactive visuals, built on one semantic model | Desktop or the service |
| Dashboard | One page of tiles pinned from one or more reports | Only in the service |
| Workspace | A shared folder for models, reports, dashboards and more | The service |
| App | A read-only package of workspace content for a wide audience | The service, published from a workspace |
When you publish a .pbix file, the service splits it into two items: a semantic model and a report. Many reports can share one semantic model.
4. Views in Desktop. The icons on the left switch between views. Report view is where you build pages. Table view (called Data view in older versions) shows the loaded rows. Model view shows tables and relationships. DAX query view lets you run DAX queries. Power Query Editor opens in its own window when you choose Transform data.
5. Licences in general terms. Desktop is free. Anyone can build and save reports locally. Publishing to your own personal area of the service is possible with a free licence. Sharing content with other people generally needs a Pro or Premium Per User licence, or a workspace that sits on a paid capacity. Some features, such as Copilot in Power BI, need a paid capacity. A free trial is often available. Prices and exact rules change, so check Microsoft’s current licensing page before buying.
Example: Campus Help Desk
In the PL-900 track you built a Help Desk with a Ticket table and a Category table. This track uses the same idea as two CSV files, so you can practise without a Dataverse licence.
- Copy tickets.csv (60 tickets from January to June 2026) and categories.csv (four categories) from the dataset panel.
- In Desktop choose Get data, then Text/CSV, and pick tickets.csv. A preview opens. It shows columns such as TicketID, CreatedDate, Priority, Status, Campus and AssignedTo.
- The preview offers Load and Transform data. Load brings the data straight in. Transform data opens Power Query first. For now, choose Load.
- Load categories.csv the same way. In Model view you may see a line between the two tables on CategoryID. Desktop sometimes detects relationships automatically.
- Add a Card visual showing the count of TicketID. It shows 60.
- Add a clustered bar chart with Campus on the axis and the count of TicketID as the value. Look closely: you may see more than three campuses, because some rows say "north" or have extra spaces. Lesson B.4 fixes that.
Later lessons turn this quick start into a proper star schema with a Date table, clean data, measures, secure sharing and scheduled refresh.
The PL-300 exam at a glance
PL-300 is the exam for the Microsoft Certified: Power BI Data Analyst Associate certification. The passing score is 700. Associate certifications are renewed every year with a free online assessment on Microsoft Learn. A free practice assessment is also available there.
| Area | Weight | Lessons |
|---|---|---|
| Prepare the data | 25–30% | B.3, B.4, B.5 |
| Model the data | 25–30% | B.6 to B.10 |
| Visualize and analyze the data | 25–30% | B.11, B.12, B.13 |
| Manage and secure Power BI | 15–20% | B.14, B.15 |
Common mistakes
- Calling a report a dashboard. A report can have many pages and lives in Desktop and the service. A dashboard is one page of pinned tiles, only in the service.
- Still saying "dataset". Microsoft now says semantic model. The exam uses the new name.
- Thinking Desktop is paid. Desktop is free. Licences matter when you share in the service.
- Emailing .pbix files around. That breaks security and refresh. Publish to a workspace and share there.
- Choosing Load when data is messy. If the preview shows problems, choose Transform data and clean first.
How the exam asks about it
- "Single page", "pinned", "tiles from several reports" point to a dashboard in the service.
- "Distribute to many users who only view" points to an app published from a workspace.
- "Collaborate with colleagues who build content" points to a workspace with the right roles.
- "Reuse the same data for several reports" points to one shared semantic model.