Hi All,
Almost every week a friend, colleague, customers or family members (yes, family member…) ask me about Power BI Training. This is the reason I decided to write this post about Free Power BI Training and Books.
On-Line Training
Microsoft
Microsoft provides a good documentation of Power BI, including Power BI Services, Power BI Desktop, Power BI Mobile Apps, Power BI Developer and Power BI Report Server.
https://docs.microsoft.com/en-us/power-bi/
You can also download all Power BI documentation in PDF, see below: 
Microsoft provides a Guided Learning for Power BI, which helps you on what to learn first.
https://docs.microsoft.com/en-us/power-bi/guided-learning/
There are also over 140 training videos on YouTube from Microsoft Power BI Team, which are part of the “Analyzing and Visualizing Data with Power BI” course available on EdX.
https://www.youtube.com/playlist?list=PL1N57mwBHtN0JFoKSR0n-tBkUJHeMP2cP&app=desktop
EdX
EdX is an open online course provider, used by Universities and Companies to publish courses. Microsoft provides over 200 courses on EdX, including Analyzing and Visualizing Data in Power BI, which provides a great start for who wants to learn Power BI.
https://www.edx.org/course/analyzing-visualizing-data-power-bi-microsoft-dat207x-8
Udemy
Udemy is an online learning platform and also provides a Free training in Power BI “Learn Power BI Basics for Free” with 15 lectures and a total of 10.5 hours of video.
The training is delivered by Vishal Pawar and has some sections delivered by Gil Raviv, Usama Wahab, Patrick LeBlanc, Leila Elaati, Devin Knight, Reza Rad and Marco Russo.
https://www.udemy.com/learn_power_bi_for_free/
SQLBI
SQLBI is Alberto Ferrari and Marco Russo’s website with a lot of videos about DAX, Optimization, Power BI Dashboard, DirectQuery, SSAS and much more. Really recommend, but not for beginners.
Books
There are two free Power BI books from well-known Power BI experts Reza Rad, Marco Russo and Alberto Ferrari.
Marco Russo and Alberto Ferrari: https://www.sqlbi.com/books/introducing-microsoft-power-bi/
Reza Rad: http://radacad.com/online-book-power-bi-from-rookie-to-rockstar
Hope it helps you.
Thanks,
Sergio
Sergio and Sabrina Zenatti 
Thanks Sergio. I get the same query pretty often too. Thanks for the links
This is really helpful. Thanks for writing and arranging the links altogether. These are the famous people to be followed for PowerBI.
Alberto Ferrari, Marco Russo and Reza Rad