A list of open purchase and sell orders for an asset that is currently sorted by price is called an order book. The order book is used by the matching engine, a technology that executes trades for exchange members by matching buy and sell orders. All electronic exchanges are built on an order-matching system, which also defines how efficient and reliable the exchange is. Although order books typically include the same data, the layout can change based on the platform. In the past, electronic exchanges have matched buy and sell orders using centralized systems. This approach continues to be the most reliable one for facilitating electronic trade. On the other side, blockchain technology has made it possible to develop new kinds of exchanges that use smart contracts to automatically match buy and sell orders. A decentralized exchange (DEX) is the name given to this kind of exchange. Despite some performance trade-offs, it permits trading without ever entrusting funds to a central authority. Because they allow traders to assess buyer and seller interest at particular price levels, order books are important to traders. Information on potential degrees of support and resistance can be found in these data. The prospective direction of the market may be revealed by an imbalance of orders on either the buy or sell side of the order book. For instance, a high volume of buy orders around a particular level may point to a level of support. A significant number of sell orders may also point to a point of resistance. Of course, these alone do not constitute buy or sell signals. It's best practice to use additional analytical techniques to look for confirmation. Order books on some exchanges, referred known as "dark pools," are hidden from the general public.