Order Block

An order block is a concept popular in "smart money" trading styles. The idea: before a sharp move up, big players accumulated buys in a specific zone, often marked by the last down candle before the surge. If price returns to that zone, the theory goes, leftover orders may cause it to bounce again.

It is basically a sharper, more specific take on supply and demand zones. Be aware that it is a trading framework, not a proven law: nobody outside the banks can actually see their orders, so order blocks are an interpretation of the chart.