Order book explained

The order book is a list of all open buy and sell orders for a market. Buy orders (bids) are on the left, sell orders (asks) are on the right. The spread between the best bid and best ask is where trading happens.

Each row shows a price level and the total amount of shares available at that price. Green rows are buy orders, red rows are sell orders. The top of each side shows the best available price.

When a new buy order comes in at a price equal to or higher than the best sell price, a trade happens immediately. If no match exists, the order sits on the book waiting. The order book uses price-time priority — the best price gets filled first, and among equal prices, the earliest order goes first.

A "deep" order book with many orders at various prices means the market is liquid — you can trade larger amounts without moving the price much. Thin order books mean bigger price impact per trade.