Knitting: it really helps to start with an actual human teacher, but people can self-teach themselves using YouTube only. After you get the basics down, YouTube is great for learning a stitch you’ve never seen before. And that’s pretty much all you need to start reading patterns. Anytime you come across something you don’t understand, YouTube to the rescue. There is also a great community site called Ravelry for pattern discovery, discussion, and yarn information.