Hi, what you are referring to is a DOM (Depth of Market). For example, Tradestation has a DOM (or 'ladder') called 'The Matrix'. It shows the total number of bids and asks at each price level on both sides. Visually, it's easier to see when there's a large order a certain price level (always at whole numbers and usually at half dollar increments). The Montage or Level 2 (Market Depth) window, presents the same information, but in my opinion, are better. The reason is the Montage (level 2/Market Depth) window, shows each market maker at that price. Rather than aggregating everything at a price like the ladder/DOM does. This is vitally important when trying to understand what market makers/participants are trying to do a different prices.