Most of the pain and suffering that occurs in bioinformatics happens when database identifier 'A' in file 1, doesn't quite match database identifier 'B' in file 2...even when they are supposed to be the same identifier. Things don't always match up for a number of reasons, most of which *should* be under our control. This talk covers a few points relating to this and briefly discusses how we should all be using curated ontologies to describe our data.