Ask HN: What are the best learning references that have you found?

I'm looking for introductory stuff like the following:

- https://howhttps.works/

- https://howdns.works/

- https://tls13.xargs.org/

- https://beej.us/guide/bgnet/

- Eli the computer guy series on youtube (A+, Networking, Cloud Computing)

Reason for asking: i like sharing things like this to people new to programming / development in general.