General comments/chat, page-17454

they can hold a short position without expiration.

in short...
the shorter borrows the stock from a current holder and sells them.
the shorter pays interest to the original holder on the borrowed shares for the duration of the position (I've heard of interest rates in this environment of 7-9%).
the shorter buys them back on market, gives them back to the original holder, closes out his short position, and pockets the difference.

if the price drops enough to cover the cost of interest it's a successful trade, if the price keeps rising, the shorter gets burnt.