Now I am interest in the technical networks. With the progress of computing hardware complex applications are possible. Nowadays it is rather easy to get information on this area, the Internet provides access to training and documentation. It is no longer necessary to spend days in the library.
I am starting with the Google Machine Learning Crash Course (MLCC). It is a great refresher. It also is an introduction to TensorFlow, a Python framework for machine learning. And you get access to a platform to run the programming exercises, no need to buy a fast computer.
I am positively surprised that I can still remember the basics, after 20 years.