The price at which a buyer is willing to willing and ready (through an order) to purchase an investment (e.g., a security, a commodity, or a derivative instrument). It is the highest price that a market participant would pay for a tradable instrument at given time.

The highest bid at a specific moment is known as a best bid which denotes the highest price at which market makers, in a given market, offer to buy an investment from a market participant at a specific time or during a particular time window. It is the highest bid price in the bid queue: on arrival of a bid price that is equal or better to the currently highest buy offer, the exchange would match the bids at the best bid, on a first-come, first filled basis.

The bid (or bid price) will almost always be lower than the ask price ( or offer price), with the difference between the bid price and the ask price being the “spread” or the bid-ask spread.