Mt.Gox Graph Question This is the last month's graph:



And this is the last day's graph:

So these are my questions:


If the today's price is about 800$ in daily graph, why is the today's price displayed as about 200$ in montly graph?
What does tell the mini graph tell us below the main graph?
What is meant with the Volume? If it's the traded amount, why should i bother with it, instead of directly looking at the amount price movemont?


PS: By the way, to see the graphs larger, click on the corresponding image with the right mouse button and then click on view image.
The numbers for the price are on the right of the graph (under the word Price that is turned 90 degrees clockwise) and the numbers on the left are for volume (under the word Volume that is turned 90 degrees counterclockwise.

Price is the amount that was paid on a per-bitcoin basis, the "candles" show where trading occured during the time period in question and the "wicks" show spikes in those same time periods.

Volume is the number of bitcoins bought and sold during a given period, with each period being represented by a direction change on the line graph. This is an important metric because it shows how much trading is happening, whether or not the price is changing significantly (since many people might buy/sell at some times/prices and other times there are few available bitcoins at a given price.)

Price will always remain the same at different levels of zoom, but volume will change based on the number of trades that happened, and since zooming changes the size of the periods (daily in the top, hourly in the bottom) the volume numbers on the left will shift as needed.

The mini-chart allows you to see the volume of the exchange over a very long period, and the highlighted section is what you are currently looking at in the chart above. You can adjust the scope of the main graph by pulling the handles on the mini-graph if you want to see a period of time in more or less detail, or select a specific period of time (like October)

To get more information on asset pricing charts I recommend http://stockcharts.com/school/doku.php?id=chart_school:chart_analysis and for other bitcoin specific charts and graphs be sure to check out http://bitcoinity.org, http://bitcoinwisdom.com, and http://bitcoincharts.com/charts