Order flow, explained in plain English

The market is an auction

Forget "bulls versus bears" cartoons for a moment. A market is a continuous two-sided auction. Price moves up when aggressive buyers are willing to pay the asking price faster than sellers can supply it, and down when aggressive sellers hit the bid faster than buyers can absorb them. Order-flow tools simply let you watch that auction instead of guessing at it from a finished candle.

Two kinds of participants matter:

• Aggressive (market) orders — traders who cross the spread and take the available price right now. These move price.
• Passive (limit) orders — traders waiting at a price with resting orders. These form the "book" and can absorb aggression.

Order flow is the interaction between the two. Everything below is a different window onto that same interaction.

The core concepts

1. Footprint charts

A footprint chart breaks each candle open and shows, at every price level inside it, how much volume traded at the bid versus the ask. Instead of one candle you see the fight that produced it: which prices were attacked, which were defended, and where the one-sided pushing happened.

2. Delta

Delta is the net difference between aggressive buying and aggressive selling over a period:

Positive delta means buyers were the aggressors; negative delta means sellers were. Cumulative delta adds delta up over the session, giving you a running score of who has been pushing — and, importantly, whether that pushing is actually moving price (see absorption, below).

3. Bid/ask imbalance

When one price level trades, say, three or four times more volume at the ask than the neighbouring level traded at the bid, footprint software flags an imbalance. Stacks of imbalances in one direction show momentum inside the candle — a useful clue about who was in a hurry. It is a clue, not a crystal ball: imbalances fail constantly, which is why context and risk rules matter.

4. Absorption

One of the most valuable patterns to understand. Absorption is when aggressive orders pour in — huge delta — but price refuses to move, because a passive buyer or seller is quietly absorbing everything with limit orders. Heavy selling that cannot push price down often means a large buyer is happy to take the other side. Watching effort (delta) versus result (price movement) is the heart of order-flow reading.

5. Liquidity

Liquidity is the depth of resting orders available to trade against. Thin liquidity — early Asia session, holidays, the seconds around a data release — is why price can jump several pips on modest volume: there is simply nobody home at the prices in between. Beginners consistently underestimate how much of "random" movement is just thin liquidity.

6. Volume profile

Volume profile rearranges volume by price instead of by time. It highlights:

• POC (Point of Control) — the price where the most volume traded; the session's centre of gravity.
• Value Area — the range where roughly 70% of volume traded; prices the market broadly "accepted".
• High/Low Volume Nodes — shelves of heavy trade (acceptance) versus thin zones price tends to move through quickly (rejection).

7. VWAP

The volume-weighted average price is the average price of the session weighted by how much traded at each level. Institutions use it as a benchmark; short-term traders use it as a fair-value reference. Price far from VWAP is "expensive" or "cheap" relative to the day's business — context, again, not a signal by itself.

How to practise this

1. Pick one instrument and one session (for example, the London open on EUR/USD) and watch it at the same time daily.
2. Journal what you observe — delta behaviour, absorption, where the POC sits — before you journal any trades.
3. Paper trade only after two weeks of observation notes. Log everything in the journal template.
4. Review weekly: did price follow aggression, or was aggression absorbed? That single question will teach you more than any indicator stack.

Next: the events that can override all of the above in one second — the economic calendar.