Bid price

Bid - the price at which the base currency/asset is bought on the market at the current time, i.e. for a trader - the selling price. Sell trades are opened at the Bid price, because when you open a Sell trade, you give an order to the broker to buy the base currency/asset now, committing to buy it back from the broker later at the price that will be on the market at the time the trade is closed. Buy trades are closed at the Bid price because when you close a buy trade, you sell the base currency/asset at the price in the market when the trade was closed.