What is a carrier trackind id?

Ok so I bought a cd from Amazon and when I got the e-mail it had no tracking number, just a carrier tracking id. So I go to the USPS website and try to track it but it says that such tracking number sh*t doesnt exist. Could someone PLEASE tell me what an effing carrier tracking id is, and how I can track it? Also if it helps the stupid number they gave me was 0762325