From the janitors who replace the toilet paper at Area 51 to the team that gathers intelligence for the Joint Special Operations Command to the most highly trained signals intelligence collectors at the National Security Agency, an enormous amount of taxpayer money is spent trying to keep what these entities do on a daily basis a secret. And for good reason.

But the government often trips over itself to obscure even the basic outlines of secret units, even when in an age of ubiquitous information when it's hard to keep quiet about anything.

About three-quarters percent of the information you'll read below has been compiled from official government sources writing in unclassified papers and on their LinkedIn profiles. The rest comes from my reporting. No real secrets were harmed during the course of this production; I've left out several entities whose very existence is properly (at least to me) classified.