Order flow is the real-time sequence of buy and sell orders interacting in a market — the executed trades and the resting bids and offers in the order book that together determine price. Where a candlestick summarizes a period into four numbers, order flow is the underlying activity that produced them.
Traders who watch order flow use tools like the depth-of-market ladder, time and sales, and footprint charts to see where aggressive buyers and sellers are hitting, where large resting orders sit, and whether a move is backed by real participation or thinning out. The aim is to read intent and absorption directly rather than infer it from candle shapes after the fact.
Order flow is granular and tends to suit very short-term execution; it is also data-heavy, venue-specific, and easy to over-interpret, and in fragmented or crypto markets a single venue’s book is only part of the picture. Many retail “smart-money” concepts — liquidity, order blocks, imbalance — are simplified, candle-level proxies for order-flow ideas rather than the order flow itself.