user7615: I wonder these exchanges, e.g. mtgox , bitstamp, bitcoinChina...etc, are they using API to connect to each others? 
or they just closed exchange, the price sync are from the free market?

user7636: Prices are determined by free market forces. The free market prices coins different on each exchange due to liquidity, fees, fiat conversion options, and terms. Prices follow similar patterns over time, but it is traders that determine what the price is. 

user10274: Once, there will be a distributed exchange for distributed currency called "Bitcoin". 
But now, there is no connection between exchanges, you can check this right here.
See how dramatically differ from each other exchanges, because it is 3rd bitcoin bubble.

935.00 Mt. Gox 
905.82 btc·e 
840.00 Vircurex

When there is upper trend, you might see difference in 200$-300$ (30%-40% of top latest price).

7615: <p>I wonder these exchanges, e.g. mtgox , bitstamp, bitcoinChina...etc, are they using API to connect to each others? </p>

<p>or they just closed exchange, the price sync are from the free market?</p>
 7636: <p>Prices are determined by free market forces. The free market prices coins different on each exchange due to liquidity, fees, fiat conversion options, and terms. Prices follow similar patterns over time, but it is traders that determine what the price is. </p>
 10274: <p>Once, there will be a <strong>distributed</strong> exchange for <strong>distributed</strong> currency called "Bitcoin". </p>

<p>But now, there is no connection between exchanges, you can check this right <a href="http://bitcoincharts.com/markets/" rel="nofollow">here</a>.</p>

<p><a href="http://bitcoincharts.com/markets/currency/USD.html" rel="nofollow">See</a> how dramatically differ from each other exchanges, because it is 3rd bitcoin bubble.</p>

<ul>
<li>935.00 Mt. Gox </li>
<li>905.82 btc·e </li>
<li>840.00 Vircurex</li>
</ul>

<p>When there is upper trend, you might see difference in 200$-300$ (30%-40% of top latest price).</p>
