what is definition of "unique hits",and how i can check about unique hits for my domain/web site. thanks
"unique hits" means how many unique people (unique IP addresses) visit your site. You check unique hits of your website in the CPanel of your hosting account. Or if your host has no CPanel, you can try e.g. StatCounter.com. You will install an invisible counter (a script) to your website and this script will track your visitors. You will then be able to check your visitors statistics in your StatCounter account.
A Hit is really a very old term. Say you have one web page which contains 5 pictures, that would make 6 hits just to view that page for a new visitor. The next time they visit your site, their browser may cache the 5 pictures and if your web content is the only thing that changed that the second time they access, it would be 1 hit as their browser will download the web page and the 5 images would not need to be downloaded as they are access from your harddisk. It happens if you visit multiple pages from the same website and the page layout images remain the same. Most important is change out the number of visitors as that tells you how many people actually visit your site.
Uniques hits does not really matter, unique visitors does. Awstats will give unique visitors but is not 100% accurate