When it comes to learning general relativity or differential geometry from textbooks, the most annoying thing is that very few books do a good job of explaining clearly what do contravariant and covariant components mean and what tensors actually represent. Even if you get a copy of the most popular introductory texts of GR, the authors usually assume that you already know the basics of tensors and either skip the explanation or explain it in a very abstract mathematical way, which makes it even more confusing. Actually, a poor explanation of tensors and even vectors is one of the main complaint of students. But don’t worry — everything can be learned, especially these days when we have the all-mighty internet. Here are three videos that actually do a good job at teaching you the required basics. The first two are about the difference between covariant and contravariant components of vectors, whereas the last one is the simplest and clearest explanation of tensors that I’ve found.