What is it, exactly?

Tether is a cryptocurrency whose promise is that it is always worth a dollar.

Tether depends on two properties:

There are a variety of ways to kick such a project off, but let's start with a simplification. Tether borrowed $40 million (let's say) from Hong Kong banks. Then they sold the same amount of USDT for $1USD each. That's it, they're set. If they want they can give the original money back to the banks. The sale proceeds are now float and Tether is a bank with 100% reserves.

How Do You Pin It to the Dollar?

This scheme is pretty darn airtight. Tether's profit motive keeps USDT at $1.00USD. This is an "approximation algorithm" to the problem of tethering USD to the blockchain, but it is a very good approximation. See the chart. The more USDT there is in circulation, the more stable it's going to be. And, for the foreseeable future, as long as USDT is working, demand, and hence the amount of USDT in circulation, is going to grow.

Yeah, but Nobody Would Have Loaned ME $40M

  1. Oh, yes they would have. Anybody who talked to the right people would've gotten this loan. You can actually structure it so that there is 0% risk to the investor. Kids get million dollar loans for far stupider ideas.
  2. You could ICO this without any starting capital: simply delay the renewal date or promise some future proceeds to the initial buyers.

Is Tether Safe?

Some have accused them of lying about the original loan. It looks legit to me, but the point is entirely moot. After the Tether "ICO", it doesn't matter whether they had the money or not: Their obligations are covered and they can operate as a bank.

Yeah, but what if they run away with my money?!

If you had a money printing press, would you do anything to endanger that fact? Trust in Tether works for the same reason trust in a bank works: there's too much money in staying legit. They could mismanage the company and go under, but so could any bank.

Where Does the Demand Come From?

It's a convenient way to park other crypto money in a less volatile place (e.g., during forks). Some have said such exchanges represent untaxed "like-kind" transactions, but I am not an accountant and don't know. Beyond that, these dollars have all the nice transfer properties of a cryptocurrency. But since it isn't actually a dollar, it's technically not regulated like dollars are (yet).