If I've understood the question...
It's an auction, like Ebay.
The exchange plays the role of EBay. It does not itself set the price.
It's the sellers and buyers who decide their prices.
Trading 'at the market' means buying or selling at the best available price.
(And some other details)...
Talking about the angle of, say, a roof makes sense because both the horizontal and vertical units are the same, i.e. spatial, units of distance. If I state my roof is 45 degrees, then this is meaningful to anyone without further context.
But if I say the trend on my chart is 45 degrees, what...
Back "a few" years ago deciding to power on a desktop machine and then sit down at a dedicated computer desk required a certain amount of commitment. (I won't mention dial-up modems, Netscape, Windows 3 or turbo buttons.)
In contrast, 'Swipe n Like' culture today - swiping one's finger across a...