The bid/ask spread is how market makers make money by offering different prices for buying and selling stocks or options. The bid price is what the market is willing to pay for your stock, while the ask price is what they want you to pay to buy it. The difference between these prices is called the spread. The spread is wider for in-the-money options because market makers need to hedge their positions with a large number of shares. This spread is influenced by implied volatility, which measures the market's expectations for future price movements.