user141: If Bitcoin trading never stops then what does it mean when news sites and others talk about bitcoin opening or closing at a certain price, and why is this terminology used?
Could two people mean different things when they talk about the closing price at the same date? (apart from price differences between exchanges)

user5406: Traditional markets are not open for trade all day, so the opening and closing price refer to the first and last price of the day. They are used as measurements for the trading activity of a day.
Since Bitcoin exchanges are open 24/7, I would expect the opening price to refer to the price at midnight and the closing to refer to the priceat 23:59:59 in the exchange's respective timezone. Since closing of the previous day is essentially the same as opening of this day, some pages such as e.g. CoinDesk only show the closing values for the historical data.
Closing price should always be the last price of the day, so it should be unambiguous.

user12891: For the Gemini exchange the closing price is at the time of their daily auction at 4pm ET.  
You can read more about the auction here:
https://gemini.com/marketplace/
And why it is considered their "end of day" price here:
http://www.coindesk.com/winklevoss-exchange-gemini-bitcoin-auctions/ with a quote from one of their founders.

user5292: In 24 hour markets High and Low usually mean "highest/lowest price in last 24 hours". 
Open generally refers to the price at 12:01 AM UTC of any given day and close generally refers to the price at 11:59 PM UTC of any given day.

141: <p>If Bitcoin trading never stops then what does it mean when news sites and others talk about bitcoin opening or closing at a certain price, and why is this terminology used?</p>

<p>Could two people mean different things when they talk about the closing price at the same date? (apart from price differences between exchanges)</p>
 5406: <p>Traditional markets are not open for trade all day, so the opening and closing price refer to the first and last price of the day. They are used as measurements for the trading activity of a day.</p>

<p>Since Bitcoin exchanges are open 24/7, I would expect the opening price to refer to the price at midnight and the closing to refer to the priceat 23:59:59 in the exchange's respective timezone. Since closing of the previous day is essentially the same as opening of this day, some pages such as e.g. CoinDesk only show the closing values for the historical data.</p>

<p>Closing price should always be the last price of the day, so it should be unambiguous.</p>
 12891: <p>For the Gemini exchange the closing price is at the time of their daily auction at 4pm ET.  </p>

<p>You can read more about the auction here:
<a href="https://gemini.com/marketplace/" rel="noreferrer">https://gemini.com/marketplace/</a></p>

<p>And why it is considered their "end of day" price here:
<a href="http://www.coindesk.com/winklevoss-exchange-gemini-bitcoin-auctions/" rel="noreferrer">http://www.coindesk.com/winklevoss-exchange-gemini-bitcoin-auctions/</a> with a quote from one of their founders.</p>
 5292: <p>In 24 hour markets High and Low usually mean "highest/lowest price in last 24 hours". </p>

<p>Open generally refers to the price at 12:01 AM UTC of any given day and close generally refers to the price at 11:59 PM UTC of any given day.</p>
