We live in an era of digital money: you can use your smartphone to make transactions. But it’s still hard to get a sense of what it means. How many transactions are there? How big is the market? Who controls it? It’s like asking how many people in the world have smartphones.

Bitcoin was the first digital currency, but it has had four competitors since. Here are five that are likely to be especially interesting in 2019.

The most interesting coins in the world are the ones you don’t see. Bitcoin is one of them. It isn’t a coin made of gold or silver; it’s a kind of program that operates on computers around the world, and the computers from which it runs to find other computers that need to run it. If you want to play games or run websites or make music, you can use these computers. And if enough of them do, they will become as important to our civilization as electricity.

But what is bitcoin? It’s not a coin at all. It’s an idea: a set of monetary formulas, based on cryptography, that many people have agreed to work with. And it has been growing in popularity because it works so well and is so easy to use. The more people who use it, the more value there is in using it. Like any good idea, it has been copied by other people so much that we actually don’t know how many copies there are.

It’s one of the few things it’s OK to be honest about in crypto. There are basically two ways to look at crypto. You can think of it as a way to trade in value-free assets, like stocks and bonds, but with better security and lower cost. Or you can think of it as a means to make money by trading in value-free assets.

Crypto is no more value-free than any other asset class. But there are a few reasons why this doesn’t matter much. To start with, banks do not charge their customers interest on deposits. Nobody pays most bondholders for the privilege of lending them money, and people buy stocks rather than raise money by selling shares on the stock market because they believe that owning shares confers some kind of benefit on them, not because they think they will get interest when they deposit money. (Banks do charge fees, but they’re tiny compared to the total interest paid.)

All these things are perfectly OK if you’re investing your own money and you know what you’re doing–and if you don’t know what you’re doing then it’s still OK for the same reason that it’s OK for your broker to charge you commissions: If you realize the amount of risk is high enough,

The idea of a crypto coin is very attractive. It’s like a piece of money you can keep and spend, except that you don’t have to pay interest or taxes on it. Also, the coins are digital (which, in principle, means they’re almost impossible to steal or lose) and, since you have total control over them, they are essentially un-stoppable. The only thing they can be stolen from is you.

But they are not really un-stoppable, any more than your credit card is un-stoppable. They depend on the internet being available and working; they rely on computers working; and they rely on people not getting hit by trucks. If one of these things fails temporarily, your coins will fail too. You’ll have to wait until there’s a reboot before you can get them back up again.

And even if all three things don’t fail, you’ll still need to sit down every few months and write down a list of what you own — just like you do with gold.

There is a phenomenon in which the more people know about something, the less they seem to care. In the past few years, things like Bitcoin and Ethereum have been getting a lot of attention. But even as Bitcoin has become more widely known, it hasn’t lost its mystique; it is still seen by many as a dangerous, dodgy thing, even though it has become much more widely used.

The explanation is that “mining” is just a side effect of specialized mining. If you mine gold with a shovel or by panning for gold in a river, there is no question what “mining” means. But if you have specialized software that mines large numbers of blocks at once, then mining can seem mysterious and other people’s motives suspect.

Bitcoin is a kind of crytocurrency, although it is not really a currency at all. It is an electronic payment system that uses cryptography to secure the transactions.

It is like cash but without physical notes or coins. Like cash, you can use bitcoins for buying things. But like PayPal and credit cards, you can also use them to make other kinds of payments, such as paying for flights or hotels. And like many other payment systems, you can use bitcoins to pay people online.

Bitcoin has some advantages over traditional payment methods: there are no fees and you pay the merchant in bitcoins directly; there is no need to ask your bank for permission. The disadvantages are that it is not extremely easy to use (you need to understand how to transfer bitcoins), and it can be risky if someone steals your internet connection while you are transferring money online.

We are now living in an era of extraordinary wealth, but that does not mean we are living in unprecedented times of danger.

A few years ago it was assumed that the world was getting less violent, not more so. Since 2000, however, there has been an explosion of terrorism around the world, alongside a rise in organized crime and drug-related violence.

There have also been signs of increasing conflict between ethnic groups in different parts of the world. In the United States, for example, there have been shootings at colleges and high schools, as well as clashes between minority groups and police. This follows a period when police officers killed unarmed black men with impunity.