The bid/ask spread is the difference between the bid price and the ask price. The bid is the price someone is willing to pay, and the ask is the price someone is willing to offer. Spreads that are more narrow are indicative of good liquidity, and typically offer better pricing opportunities.
Yes, itan indication of liquidity
To see the bid-ask spread in real-time you will need to monitor your brokerage platform.
Spreads that are more narrow are indicative of good liquidity, and typically offer better pricing opportunities.
It can be used for both stocks and options.