I do look forward to seeing answers that are web tutorials as I'm trying to start in that area. Most good resources are books or courses, though. I'll give you a bit of that. For digital, the NAND2Tetris course or book at least get people hooked on it with some of the basics:
Malvin's Electronic Principles, which I got for $2 on Amazon, was also much more readable than Horowitz and Hill. Another thing to know is resources are usually almost all hands-on or all theory. Gammel's Contextual Electronics course that bradfa links to below was said to be in the middle somewhere. Also, if digital, you might want to make a note of "High-Speed, Digital Design" for later along with some book on verification either formal or "design-for-testing." Some people also do FPGA cookbooks and such if they're working with them. For RF, most people have one by ARRL or something whose name I can't recall. Finally, for electromagnetic compatibility testing, the great article and conversation linked below has a book in it.
http://nand2tetris.org/book.php
For analog electronics and PCB's, the latest list of books I found was this:
http://www.circuitstoday.com/4-great-books-to-study-basic-el...
Malvin's Electronic Principles, which I got for $2 on Amazon, was also much more readable than Horowitz and Hill. Another thing to know is resources are usually almost all hands-on or all theory. Gammel's Contextual Electronics course that bradfa links to below was said to be in the middle somewhere. Also, if digital, you might want to make a note of "High-Speed, Digital Design" for later along with some book on verification either formal or "design-for-testing." Some people also do FPGA cookbooks and such if they're working with them. For RF, most people have one by ARRL or something whose name I can't recall. Finally, for electromagnetic compatibility testing, the great article and conversation linked below has a book in it.
https://news.ycombinator.com/item?id=15440411
Hope some of this helps.