A friend, who is interested in machine learning but comes from a more traditional DBA / data engineering background, recently asked me how he could get started in the field. While we have a number of great resources here at DataRobot to help start your machine learning journey (DataRobot University, the DataRobot blog, our YouTube video series, etc.), it may also be helpful to pair them with freely available courses.
So the below list is what I've found useful to either gain or enhance my machine learning knowledge over the years. All of the resources below, with the exception of the two books below, are freely available.:
What are other great (free) resources people have used?
Hands-On Machine-Learning with Scikit-learn and Tensorflow is a great book for getting started! I always look back at it for reference when I need to review a topic.