Personally I like books, but there are also many, many lecture videos on YouTube, some of them excellent (though I think they could still be better with bigger production teams and higher budgets). For college-level technical subjects, there are also e.g. many MIT lectures on OCW. If you have a specific topic in mind, I urge you to search around. (Making a long list of my own book/website/video recommendations about various topics here seems a bit off topic and out of scope.)