This is a great article by Scott Meyers: Universal References in C++11
It explains what rvalues are in a very clean and concise way. This is the best explanation that I’ve found so far. All the other descriptions of rvalues and rvalue references are detailed, but too complicated…
The main topic of this article is that T&& in C++11 not always indicates an rvalue reference, but sometimes it indicates what he calls a universal reference, which is collapsed by the compiler to either an lvalue reference or rvalue reference, depending on T!
Worth a read, even as a refresher.