What does mean Avg Position from Google Webmaster Tools

Any one explain me, what is the avg.position on Google webmasterr tools. i see my keywords and avg.positions.

examle - one keyword shows that avg.position is 4. Is this that keyword rank ?

In Google Webmaster tools, The “Avg Position” shows the position of your website on the SERPs for that particular keyword search.
for example: If your site comes up half the time in position 5 and half in position 10, then your average position should show up as 7.5.