The two, biggest problems in IT are cache invalidation and naming things. The third one, I think, is legacy code. If you’re not working in a startup, which has just been founded, chances are, you need to deal with some sort of legacy application. For a majority of my career as a developer, I was working in one company. It was great, but we’ve had to maintain an application, which was created around year 2002! That’s when Napster was shut down! Today, this application is still running, but since a few yea...