What is the best way to keep track of UV's

I am looking for a way to figure out how many unique visitors I have. I found a website that did it for free. It claimed I had 174 UV today however I don't believe that I could have had that many. As my google adsense account only listed 15 impressions.

So I am looking for a software or website that can accurately keep tabs on my unique visitors and where they are coming from. Preferably for free.

What do you know that can do this?

Thanks for the help
Wooba

 

Google analytics also showing unique visitor with bounce rate

 

Google Analytics

 

Also awstats is good tool to analyze stats which you can access through your cPanel.

 

Ok Im already in the process of setting it up, what about, if I want to check the statistics on another site?

 

Like mentioned above Google anyltics but a long time favorite is Stat Counter.

 

You may also try to use the sitemeter where can also track your UV, page impressions, page views and many more.. Just click the counter badges you can now be tracted yous sites stat. Either sitemeter or statcounter that's the accurate for tracking your sites statistics.