Any explanation that’s going to fit in an HN comment is going to be oversimplified, but it’s basically a derivative instrument tracking some underlying. It’s paired/netted (ish) so you can go short if someone wants to go long (ish).

If the derivative (“perp”) is trading above the underlying then longs pay shorts a fee on some cadence, making long positions progressively less attractive holdings and creating sell pressure. Vice versa.

This tends to push the derivative close to the underlying.

This has two big advantages and a shitload of problems. The two advantages are:

- short sentiment can be expressed without an up-front load, kinda like a put

- entering a position is much like a CME future, you don’t have to put up the whole price, just wherever geometric Brownian motion is likely to set you back (“implied leverage”)

Used responsibly this isn’t insane, but the ways it can be abused? Think housing never goes down in 2007.

If you are in the US and want to user perpetual swaps you are basically SOL. Unless you want to use a decentralized exchange.

I’m the last person to take any legal advice from, and I don’t personally trade crypto whatsoever, so caveat emptor.

I’m not aware of any law that stops you asking a friend to put a trade in on your behalf as long as you pay appropriate taxes.

Check with someone who knows before doing it though because I could be totally wrong!