The lowest price the seller accepts right now. You pay it when you buy the option.
What this price is
The ask price (Ask) is the lowest price sellers accept right now. It is what you pay for an immediate entry. Together with the bid price (Bid, the highest price buyers will pay) it forms the two edges of every trade, and the distance between them, the spread, is the cost of immediacy.
Who stands at the two edges
Most of the people on the bid and the ask are market makers who earn from the spread itself. They buy at the bid, sell at the ask and neutralize their exposure by hedging. When uncertainty rises (a scheduled event, a violent move) they widen the spread or step back, and liquidity dries up just when it is needed most.
The bid-ask spread matters more in options
A spread of a few cents on a stock can mean tens of cents on its options. A contract is almost always less liquid than its underlying. So the quality of any options idea is judged by the liquidity of its contracts before the merit of its direction: a correct idea in a contract with a 15% spread needs an exceptional move to clear the cost of getting in.
Hypothetical example
A limit order to buy at $1.05 on a contract with an ask of $1.10 and a bid of $1.00. It may fill within seconds if either side moves a little, saving the full 5% versus a market order. It may also not fill. That is the price of patience.
Common mistake
Judging a trade's profitability on paper at mid prices and then executing with market orders. The gap between the two calculations is exactly what turns strategies that win in theory into losers in practice.
Why the size of the spread matters, not just the price
The gap between bid and ask is the cost of immediacy. Someone who buys at the ask and sells at the bid pays the gap twice in one round trip. In thin contracts the gap can swallow half the premium, and a four-leg structure is a loser before the market moves a cent.
Where to see it on the platform
The options chain shows both edges for every contract, and the options calculator uses whatever price you enter. Comparing mid price with actual execution is up to you.
The options chain shows the spread for every contract, so you can measure the cost of entry before you commit.
