Its an offer of setting price of someone who is willing to pay for something

1. An offer made by an investor, a trader or a dealer to buy a security. The bid will stipulate both the price at which the buyer is willing to purchase the security and the quantity to be purchased. 2. The price at which a market maker is willing to buy a security. The market maker will also display an ask price, or the amount and price at which it is willing to sell.

Indication of willingness to buy or sell goods or services or to undertake a task at a specific price and within a specific timeframe.