It is the shared marketplace where nations, corporations, and alliances list resources and military goods. You place limit sells or buy with quantity; the server matches compatible prices when someone else arrives.
Each row is someone willing to sell at that price. Cheaper asks appear first. The bar shows cumulative size so you can see depth.
Each row is someone willing to buy at that price. Higher bids appear first.
The third column shows the trader (nation name, corporation name, or alliance name when available).
Pick a resource tab, stay on Buy, enter quantity, complete the security check, and submit. Buys walk the book from the cheapest ask upward until your quantity is filled or offers run out.
Switch to Sell, set your limit price per unit, enter quantity, then submit. Your order waits until a buyer's price is at least as high as your ask (for the same resource). Nations cannot list bio-weapons for sale; corporations can where rules allow.
The chart needs aggregated trades over time. New or quiet markets may show "no history yet." After volume builds, candles appear for the timeframe you select (1H, 4H, 1D).
Normal spread: Best ask (lowest sell) minus best bid (highest buy). Tighter spread usually means a more active two-sided market.
Crossed book: If the best sell is lower than the best buy, the screen is showing overlapping limit orders that have not cleared yet. In the real world that would arbitrage instantly; in a busy game it can appear briefly. Refresh and watch recent trades; the guide on the exchange page links here for detail.