There are books from oreilly and paid MOOC courses that are just padded with lots of unnecessary text or silly "concept definition" quizzes to make them seem worth the price.
And there are excellent free YT video lectures, free books or blog posts.
Andrej's YT videos are one great example. https://course.fast.ai is another.
If the web page /content is too polished, they're most likely optimizing for wooing users.
Unlike a lot of the examples I gave in the sibling comments. Where the optimization is only on the love for the topic being discussed
There's an inverse correlation with the glossiness of the content as well.
i.e. Berkson's Paradox: https://en.wikipedia.org/wiki/Berkson%27s_paradox
There's also a tremendous amount of extremely low quality YouTube and blog content.
But from my limited sample size, the best free content is better than the best paid content.
- beej's networking guide is the best thing for network layer stuff https://beej.us/guide/
- explained from first principles great too https://explained-from-first-principles.com/
- pintos from Stanford https://web.stanford.edu/class/cs140/projects/pintos/pintos_...
Andreas Kling. OS hacking: Making the system boot with 256MB RAM https://www.youtube.com/watch?v=rapB5s0W5uk
MIT 6.006 Introduction to Algorithms, Spring 2020 https://www.youtube.com/playlist?list=PLUl4u3cNGP63EdVPNLG3T...
MIT 6.824: Distributed Systems https://www.youtube.com/@6.824
MIT 6.172 Performance Engineering of Software Systems, Fall 2018 https://www.youtube.com/playlist?list=PLUl4u3cNGP63VIBQVWguX...
CalTech cs124 Operating Systems https://duckduckgo.com/?t=ffab&q=caltech+cs124&ia=web
try searching here at HN for recommendations https://hn.algolia.com
Disclosure: Professor Malan is a friend of mine, but I was a fan of CS50 long before that!
Fellow hackers might also enjoy:
I like the book better than the online course.