Investment - The  Bid, Ask and the Spread 
In markets that are driven by quotes, dealers' willing-to-buy prices are referred to as bid prices, while their willing-to-sell prices are referred to as ask prices or offer prices. Every time, the ask prices are greater than the bid prices. 

Additionally, dealers have the option to list the quantities (also known as bid sizes and ask sizes) that they will trade at the bid and ask prices. These sizes could or might not be visible to other dealers or traders in that market, depending on the trading venue. 

When dealers disclose their bids and offers, it is referred to as quoting the market. They frequently quote a two-sided market, which includes the bid and ask prices. The best bid is the one that is placed highest in the market, and the best ask is the one that is placed lowest. The market bid-ask spread is the difference between the best ask and the best bid. Generally speaking, the market bid-ask spread is never more than the dealers' bid-ask spreads.

because dealers frequently offer prices that are more favorable on one side of the market than the other. As a result, multiple dealers frequently submit the best offer and best ask.