What Is a ‘Limit Order Book’ and How Is It Visualized for Depth Analysis?

A limit order book (LOB) is a real-time record of all outstanding limit orders for a financial instrument, organized by price level. It is visualized for depth analysis as a cumulative graph showing the total volume available at each price level on both the bid (buy) and ask (sell) sides.

The shape of this curve indicates market depth; a steeper curve means less depth, and a flatter curve means more depth.