Cryto is a family of cryptographic techniques for transforming information in such a way that even if someone knows the original message, they can’t figure out what it was. It’s also a family of schemes by which these techniques are used. One of these schemes, called asymmetric cryptography, has become widely used. Cryptography is the science of protecting information from eavesdroppers and other snoopers. In practice, cryptography is a technology that allows you to exchange information secretly.

Today’s cryto isn’t much different from the cryto of an earlier time: Julius Caesar invented one form of cryto and used it to send secret messages to his generals in Gaul; he made his own messages unreadable by anyone but himself and his most trusted confidants.

The most important thing to remember about cryto is that it is not magic. Cryto is a science. It’s more like chemistry than like magic. Cryto is like chemistry in the sense that there are formulas, and those formulas can have practical applications. Cryto is more like alchemy than chemistry because it involves things we cannot see and cannot touch: forces and effects beyond the range of our senses.

Cryto seems to have been invented by either William Friedman or Frank Rowlett (the names vary). They called it “crystallography,” which is a mouthful if you’re going to be writing about it, but easier on the tongue if you’re going to be writing about it for a living. But whatever you call it, it’s just another name for something that already existed: cryptography.

Cryto is a shorthand for cryptography, the field that deals with secrets and the ways we keep them. Cryptography has become at least as common as, and even more popular than, the computer revolution. But it’s an old idea; the Greeks used it to keep their city-states secure from invasion.

In our time, cryptography has been applied in many different areas: banking and finance, computers and phones, email, web browsing, cars and airplanes, voting machines and medical records. It’s hard not to notice that we generally have no idea what it all means.

It’s true that cryptography isn’t magic; you don’t get a secure phone call by rolling dice or waving your mobile phone over a candle. But if you want to understand why this stuff matters so much, you need to understand what it isn’t. It’s not something new or special; it doesn’t require any particular expertise to be applied; there are no mysterious discoveries about how it works; and no one can make a profit from teaching it.

Crypto is a way of moving wealth. Bitcoin is one of several hundred such things, but it is the most well known. Most crypto-things are complicated and hard to understand, so that most people don’t even know what they are. But if you know what they are and you understand them, they can be very profitable.

Bitcoin was created in 2008 by a pseudonymous person or group called Satoshi Nakamoto. It took off in 2010, when not much was known about it. A lot of people got involved with it, but most of them didn’t really understand how it worked. That’s because bitcoin is open source software.

Open source software, like Linux or Firefox or Minecraft, is a set of instructions for making something that works. The instructions come from one person or group and are published so other people can use them. Open source software has many advantages over closed-source software: it’s more secure and more flexible, and you can fix bugs yourself if you want to. But the biggest advantage for bitcoin is that anyone who understands how it works will be able to make money by trading it for goods or services that others want to buy with bitcoin.

Cryptography is the art of writing things that can only be read by other people, so that if you want to send them, no one else can. It’s an ancient art, invented by the Sumerians in 2000 BC, and it has been used ever since as a way of keeping things secret.

The difference between cryptography and simple encryption is like the difference between off-the-shelf software and creating your own crypto: simple encryption encrypted plaintext to ciphertext; cryptography encrypted plaintext to ciphertext that could only be read by someone who knew the passphrase.

In practice it is useful to have both methods, because they have different strengths and weaknesses. For example, simple encryption and cryptography are both useful for encrypting messages. But simple encryption can be broken with enough time, whereas cryptography cannot.

Cryptography is the art of secret writing. The first use of cryptography was in ancient Egypt, and the earliest known written example of it is the Rosetta stone (it’s not really a true encryption; the hieroglyphs aren’t pronunciations of anything). But not only can history teach you how to write with a key, it can show you what happens if you don’t. Notice that the Rosetta stone is written in two languages, but both are in code.

The whole point about cryptographic keys is that if you have one set, no one else does. If someone finds another copy of your key, they can’t read your message. No matter how smart they are.

If you can’t go to the next level, you have to be able to get there on your own. If someone else knows something that you don’t, it could be a competitive disadvantage.

For example, if I write “We’re still working on our new crypto app,” my readers will assume I’m finished and move on. So if I’m not yet ready for prime time, I should start by writing a blog post entirely about crypto. It’s a way of communicating with people who know what I don’t.

The upshot is that it is useful to separate yourself from other people as much as possible.