Open a gold chart on one platform and it reads 2,406. Open a different chart, same instant, and it reads 2,411. Neither platform is wrong. One is tracking spot gold, the immediate cash price for the metal itself. The other is tracking a gold futures contract, a separate instrument that trades alongside spot and is priced off it, but is never quite identical to it. Most traders never ask which one they are actually looking at, until the five-dollar gap between two charts of the same market stops making sense.
Two different instruments, one underlying market
Spot price is the value of the thing right now: an ounce of gold, a barrel of oil, a unit of currency, for immediate exchange. A futures contract is a separate, standardized agreement to exchange that same asset at a set date in the future, and it trades on its own exchange with its own supply and demand. The two stay closely linked because arbitrage traders keep them from drifting far apart, but linked is not identical. The futures price embeds the cost of carry: interest rates, storage costs for oil, and time until the contract expires, all baked into a small premium or discount versus spot.
Why index charts look different depending on the feed
The S&P 500 cash index only exists while the New York Stock Exchange is open, 9:30 to 4:00 New York time. The E-mini S&P 500 futures contract trades nearly 24 hours a day with a short daily pause, which means every headline that lands at 2am New York time is already priced into the futures chart long before the cash market opens at 9:30. A trader watching only a cash-index feed sees a gap at the open; a trader watching futures the whole time saw the move happen gradually overnight. Nasdaq works the same way: the cash index reflects only the New York session, while its futures equivalent runs nearly around the clock.
What this means for the price you actually trade
Retail platforms typically quote a derived price built from the futures market outside cash hours and reconciled toward spot or cash levels when the underlying market is open. That is why your platform's Nasdaq quote can move at 3am even though the cash exchange is shut, and why it can differ by a handful of points from a pure cash-index number you might see quoted elsewhere. None of this is a flaw to worry about. It is simply which reference the price is built from at that moment, and knowing that explains discrepancies that otherwise look like a broken feed.
The same logic applies to WTI oil, where the futures contract you see quoted is genuinely the primary market, not a derivative of some other spot number, and to gold, where spot trades continuously in the interbank market while the futures contract adds its own session structure and expiry-driven pricing on top.
Currency pairs work a little differently again. EURUSD as most traders see it is a spot price, quoted directly between two currencies with no expiry date to worry about. A currency futures contract exists too, traded on exchanges like the CME, but the vast majority of retail forex activity happens on the spot side, which is one reason forex sessions run on the near-continuous weekday schedule described elsewhere rather than around a futures contract's own expiry calendar.
The practical habit
You do not need to trade futures directly to benefit from understanding them. Knowing that your Nasdaq or gold quote overnight reflects futures pricing, and that it can gap slightly at the cash open as the two reconcile, explains price behavior that would otherwise look random. It also explains why levels drawn purely from a cash session, like yesterday's high and low on the S&P 500, sometimes get tested by an overnight futures move before the cash session that produced them even reopens.