The terms buy/sell and bid/ask are closely related – they refer to the same pricing mechanics but from different perspectives:
• Bid (Buy price): The highest price someone is currently willing to pay for an asset.
• Ask (Sell price): The lowest price someone is willing to sell at.
When placing an order in the order book:
• If you’re selling, your order is matched against the highest bid.
• If you’re buying, your order is matched against the lowest ask.
The difference between these prices is called the spread, and it can affect both execution speed and price.