Every single trade has a buyer and a seller. That’s not an insight — it’s just math. For any transaction to happen, someone has to buy and someone has to sell. Which means that when you hear “buyers are in control right now” or “sellers are pushing price down,” you should pause for a second, because those phrases are telling you less than they sound like they are.
If every trade has both a buyer and a seller, what does it actually mean for one side to be “in control”?
The answer is that it’s not about who’s buying and who’s selling. It’s about how they’re participating. Two traders can both be buyers and be doing completely different things in the market. One is sitting quietly with an order placed at a specific price, waiting. The other is hitting the button right now, taking whatever price is available. Those are not the same action, and they don’t have the same effect on the market.
This distinction is the most useful reframe in this entire book. Instead of buyers and sellers, we’re going to talk about liquidity and aggression. Once those two words click for you, the market starts making a different kind of sense.
A limit order is an order placed at a specific price. You’re telling the market: I want to buy (or sell), but only at this price. The order goes in and sits there, waiting for the market to come to it.
If the price never gets there, the order never fills. There’s no guarantee of execution — only a guarantee of price if execution happens. The order is patient. It’s passive. It’s waiting.
This is liquidity. Limit orders, sitting at prices across the market, are what makes trading possible. They’re the standing offers — the prices at which someone has already declared they’re willing to transact. Without them, there’s nothing for the other side to trade against.
Here’s a way to picture it. Imagine a warehouse with shelves running floor to ceiling, one shelf for every possible price. The lowest price is at the bottom and the highest price is at the top. Each shelf holds whatever limit orders have been placed at that price — some shelves are loaded with orders, some are nearly empty, some have nothing at all.
Buy limit orders are on the bottom shelves and the highest shelf with buy limit orders on it is the bid price. The top shelves are filled with sell limit orders. The shelf with the lowest priced sell limit orders is the ask price. (You can remember that buyers are at the **b**ottom because both start with the letter “B”.) Everything between the bid and ask is the spread.
That warehouse is the market. Every limit order places something on a shelf. Every transaction takes something off one.
A market order is something different. It’s not patient and it’s not particular about price. It says: I want to transact right now, at whatever price is currently available. No waiting. No conditions. Just fill me.
When you click “buy” in your trading platform without setting a specific price, you’re placing a market order. It goes in and immediately sweeps the lowest available sell shelf — the ask — and executes there. When you click “sell” your order is matched with the highest buy price, the bid. This is done to get you the best available price. Market orders are always matched with limit orders. This is the only time an order actually gets executed.
This is aggression. The word fits because market orders demand something. They don’t wait for the market to come to them — they go to the market and take what’s available. They consume liquidity rather than provide it.
The whole push and pull of the market — everything you see happening on the chart — comes down to this interaction. Liquidity sitting on the shelves. Aggression arriving and taking from those shelves. What happens next depends on whether there’s enough on the shelf to handle what arrives.
That’s it. That’s the engine underneath everything.
Now, liquidity has two sides, and they sit on opposite ends of the spread.
Buy-side liquidity is buy limit orders — the bids. These are participants who want to buy but are waiting at their price. They’re below the current market price, sitting on the shelves under the bid, ready to absorb anyone who comes down and sells to them.
Sell-side liquidity is sell limit orders — the offers. These are participants who want to sell but are waiting at their price. They’re above the current market price, sitting on the shelves above the ask, ready to absorb anyone who comes up and buys from them.
When aggressive selling hits buy-side liquidity, the buyers on those shelves absorb the aggression. When aggressive buying hits sell-side liquidity, the sellers absorb it. This is how transactions happen — aggression meeting liquidity, one shelf at a time.
A quick note on terminology, because this is a place where things can get confusing.
If you’ve spent time in certain trading communities — particularly those following ICT or SMC concepts — you may have heard “buy-side liquidity” and “sell-side liquidity” used to mean something different. In that context, “buy-side liquidity” often refers to clusters of stop orders sitting above highs, and “sell-side liquidity” refers to clusters of stops sitting below lows. The idea being that price “hunts” these areas to trigger the stops.
That’s a different definition than what we’re using here, and it’s worth being clear about the difference. In this book, liquidity means resting limit orders — orders waiting to be filled. Stops are a different animal entirely, and we’ll get to them in Chapter 7. They behave more like aggression than like liquidity, which is part of why it matters to keep the definitions clean.
If the ICT/SMC framework is part of your background, you don’t need to abandon it — just know that when this book says “buy-side liquidity,” it means something specific: buy limit orders resting below the current price, waiting to fill.
So why does any of this — limit orders, market orders, liquidity, aggression — matter more than just thinking about buyers and sellers?
Because it tells you something about what’s actually happening that “buyers and sellers” doesn’t.
“Buyers are pushing price up” is vague. It could mean aggressive buyers are overrunning available sell-side liquidity. It could mean sell-side liquidity has dried up and even a modest amount of aggression is moving price because there’s nothing to absorb it. Those are completely different situations, and they call for different responses.
“Buy-side aggression is outpacing available sell-side liquidity” is precise. It tells you the mechanism. It points to what would need to change for the move to stall or reverse — more liquidity on the sell side, or less aggression on the buy side. It’s something you can actually watch for.
The vocabulary isn’t just cosmetic. It’s a way of seeing. And the clearer your vocabulary, the clearer your read.
From here on out, when we talk about what the market is doing, we’ll be talking about it in these terms. Liquidity on the shelves. Aggression arriving and taking from them. The interaction between the two producing everything you see on the chart.
That’s the language of this book. It’s worth getting comfortable with it now, because it’s about to explain everything.