How a spot order works

What "spot" means

In a spot trade you exchange one asset for another and take ownership straight away. If you buy bitcoin with USDT on the spot market, bitcoin lands in your account balance and USDT leaves it. There is no borrowing, no contract that expires later and no position that can be closed out automatically because of a margin call. That simplicity makes spot trading the natural place to start learning.

Trading pairs

Every spot market is a pair, written as BASE-QUOTE. In BTC-USDT, BTC is the base asset you are buying or selling, and USDT is the quote asset used to price it. A price of 60,000 on that pair means one BTC costs 60,000 USDT. Buying the pair spends USDT to receive BTC; selling it does the reverse.

The order book

Prices on an exchange are not set by the exchange itself. They come from the order book, a live list of everyone's outstanding buy and sell orders.

• Bids are buy orders, sorted from the highest price down.
• Asks are sell orders, sorted from the lowest price up.
• The gap between the best bid and the best ask is the spread.

The following table is a made-up example for explanation, not live data:

Side	Price (USDT)	Amount (BTC)
Ask	60,020	0.40
Ask	60,010	0.15
Bid	59,990	0.25
Bid	59,980	0.60

Here the spread is 20 USDT: the most anyone will pay is 59,990 and the least anyone will accept is 60,010.

Step by step: from click to balance

1. You choose the order type. A market order accepts the best available prices; a limit order sets the worst price you will accept. The difference is covered in market vs limit orders.
2. Balance check. The exchange confirms you hold enough of the asset you are spending and reserves it so it cannot be used twice.
3. Matching. The matching engine compares your order with the opposite side of the book. Orders are usually matched by price first, then by time: the best price fills first, and among equal prices, the earliest order fills first.
4. Fills. Your order may fill all at once or in several pieces at different price levels.
5. Settlement. Balances are updated: you receive the base asset, the quote asset is deducted, and the trading fee is applied.

A worked example

Using the snapshot above, suppose you place a market buy for 0.3 BTC. The engine takes 0.15 BTC at 60,010 and the remaining 0.15 BTC at 60,020.

• 0.15 × 60,010 = 9,001.50 USDT
• 0.15 × 60,020 = 9,003.00 USDT
• Total: 18,004.50 USDT, an average of about 60,015 per BTC

With an example fee of 0.1%, you would pay a further 18.00 USDT or the equivalent deducted from the BTC you receive, depending on how fees are charged. Current rates are listed on the fees page. Notice that the average price is higher than the best ask you saw: larger orders move through more of the book. This effect is called slippage.

Makers and takers

If your order fills immediately against resting orders, you are a taker: you removed liquidity. If your order rests in the book and someone else fills against it later, you are a maker: you added liquidity. Many exchanges charge different fees to each role.

Practise before you commit

Reading an order book becomes much easier once you have watched one move. The practice account on the trading terminal at /trade/ shows a live order book and lets you place orders with virtual funds, so you can see how order size, spread and fills interact without any real money involved.

Crypto assets are highly volatile and you may lose all the capital you invest.