Supply and Demand

Supply and demand is the basic tug-of-war between how much of something people want to sell (supply) and how much they want to buy (demand) at a given price. In trading, that "something" is shares, contracts, or coins, and the price you see on a chart is simply the most recent point where a buyer and a seller agreed to trade.

It works like this: at any moment there's a stack of resting sell orders above the current price and a stack of resting buy orders below it. If new buyers come in aggressively and start eating through those sell orders, price rises because each successive seller demands a slightly higher price to let go of their shares. If sellers turn aggressive instead and start hitting the buy orders, price falls as buyers only step up at cheaper levels. Price moves toward whatever level currently balances the two sides, called equilibrium, then keeps shifting as new information or new orders arrive.

In technical trading, "supply and demand" usually gets shorthanded into zones on a chart — a price area where demand previously overwhelmed supply (a demand zone, often where price bounced up) or supply overwhelmed demand (a supply zone, where price turned down). Traders mark these zones expecting that if price returns there, the same imbalance might reappear. This is closely related to support and resistance, though supply/demand zones are usually drawn as a price range rather than a single line, and the logic is framed around leftover unfilled orders rather than round numbers or prior highs and lows.

The nuance that trips people up: supply and demand zones are not fixed truths, they're a probabilistic story traders tell about why price moved, drawn after the fact. Two traders can look at the same chart and mark different zones. The zone only "works" if enough other market participants also believe it and act on it — it's a self-fulfilling pattern, not a law of physics, and it can fail the moment a large seller or buyer decides to ignore it.