Every tradable market quotes two prices at once. The bid is the highest price a buyer is currently willing to pay; the ask (or offer) is the lowest price a seller will accept. The gap between them is the spread, and it exists because buyers and sellers rarely agree on a single number at the same instant.
Spread is a rough proxy for liquidity. In a deep, heavily traded market, many participants are quoting prices close to one another, so the gap stays narrow — often a fraction of a percent. In a thin market, or during a fast-moving news event, fewer participants are willing to commit capital, so the spread widens and the visible price becomes less reliable as a guide to where your order will actually fill.
This matters most the moment you submit an order. A market order crosses the spread immediately, buying at the ask or selling at the bid, so you pay the full width of that gap as an implicit cost. A limit order lets you name your price and wait, at the cost of a fill that may never happen if the market moves away from you.
An order preview — the kind Quantiva shows before you confirm a trade — can surface the current spread, the quote source, and the estimated cost of crossing it. What it cannot do is guarantee that price still holds by the time your order reaches the book, especially in a widening spread. Reading the spread is less about predicting direction and more about pricing the cost of urgency.