C++ FAQ Celebrating Twenty-One Years of the C++ FAQ!!!
(Click here for a personal note from Marshall Cline.)
Section 8:
8.1 What is a reference?
8.2 What happens if you assign to a reference?
8.3 What happens if you return a reference?
8.4 What does object.method1().method2() mean?
8.5 How can you reseat a reference to make it refer to a different object?
8.6 When should I use references, and when should I use pointers?
8.7 What does it mean that a reference must refer to an object, not a dereferenced NULL pointer?
8.8 What is a handle to an object? Is it a pointer? Is it a reference? Is it a pointer-to-a-pointer? What is it?
[8.2] What happens if you assign to a reference?

You change the state of the referent (the referent is the object to which the reference refers).

Remember: the reference is the referent, so changing the reference changes the state of the referent. In compiler writer lingo, a reference is an "lvalue" (something that can appear on the left hand side of an assignment operator).