Market Basics · beginner · 6 min

Volume and Liquidity

Price gets all the attention, but two quieter numbers shape how a market actually behaves: volume and liquidity. They sound similar and are related, but they answer different questions — one about the past, one about the present.

Volume: how much traded

Volume is the total amount that changed hands over a period — the number of shares, contracts, or coins traded in that candle's window. On the Visor chart it's usually drawn as the histogram of bars along the bottom, one bar per candle.

Volume is a record of activity. A tall volume bar means a lot of trading happened in that period; a short one means the market was quiet. It's often read alongside price: a big move on heavy volume means many participants were involved, while the same move on thin volume means few were — a distinction traders find informative. But note the honest limit — every trade has a buyer and a seller, so volume tells you how much traded, not which side "won". Reading intent into it is interpretation, not fact, and the tape-reading track exists precisely because raw volume leaves that question open.

Liquidity: how easily you can trade

Liquidity is the here-and-now question: how easily can you buy or sell right now without moving the price much? A liquid market has lots of resting orders stacked close together, so a normal-sized order gets filled near the current price. An illiquid (thin) market has sparse orders with gaps between them, so the same order eats through several price levels to get filled.

The everyday image: a liquid market is a deep, calm pool — drop a stone in and barely a ripple. A thin market is a shallow puddle — the same stone splashes everything. In markets, that "splash" is called slippage: the difference between the price you expected and the price you actually got because your order moved the market.

Why liquidity is the hidden variable

Liquidity quietly drives things you might blame on other causes:

• Spreads. Liquid instruments have tight bid-ask spreads; thin ones have wide ones. Same mechanism — more orders stacked close together.
• How moves behave. In deep liquidity, price tends to move smoothly; in thin liquidity, it can gap and lurch, because there's little resting between levels to absorb an order.
• When it matters most. Liquidity is not constant. It dries up overnight, around holidays, and — critically — in moments of stress, exactly when everyone wants to trade at once. A market that felt liquid all week can turn thin in a panic.

Because liquidity changes with the instrument and the hour, so does the real cost and behaviour of trading it. That's a statement about market mechanics, not a suggestion about when you should act.

Seeing it in Visor

The chart's volume histogram shows the activity side. The depth-of-market ladder (the DOM widget) and the liquidity heatmaps in the tape-reading track show the resting side — how much size is queued at each price right now, which is liquidity made visible. Both come with the same caution: order-book data isn't licensed for every instrument, and resting orders can be pulled before they fill, so a ladder shows intent rather than a guarantee.

One more honest note: heavy volume or thick-looking liquidity is not a buy or sell signal. It describes the conditions you're trading in, not what price will do next. Turning "this looks like a busy level" into a rule you actually trade is where the robustness gates come in — see The Overfitting Trap.

What to read next

• The Bid, the Ask, and the Spread — the cost that liquidity sets.
• What Moves Markets — where the buying and selling pressure comes from.
• What Is Order Flow — watching liquidity and trades in real time.