Bid/Ask Spread
Difference between the highest buy offer and lowest sell offer.
Bid = highest price a buyer will pay. Ask = lowest price a seller accepts. Spread = the gap. Tight spread (BTC/USDT 0.01% on Binance) = high liquidity, low entry/exit cost. Wide (small coin with 5% spread) = low liquidity, every move costs. Spread is a hidden tax paid to market makers.
In plain words
The gap between buy and sell price right now. On BTC nearly 0%, on small alts even 5-10%.
Example
Tiny shitcoin: bid 0.0010 USD, ask 0.00105 USD = 5% spread. Entry and exit immediately cost 10%.
Also known as: spread, bid, ask