Officially IT = Information Technology, however people who refer to themselves as IT guys are normally low level twat-waffles who just like having a big bad title that makes them sound like they are smart. If they were really smart their title wouldn’t bother with saying they worked in Information Technology and instead would say something like “I design computer programs that map the human genome” etc… Now that guy is in IT but he wouldn’t want to tell somebody that because it sounds way less impressive than what he actually does.