Piwik is a free and open source web-analystics software. Different to Google Analytics (which could be seen as a privacy threat and has a monopoly position in web analytics), Piwik can be downloaded and run on your own LAMP server. Installation is a matter of minutes.
Similar to most approaches to web analytics, Piwik uses a JavaScript snippet you embed in your HTML-files for tracking. For further information on the use of this snipped, you might check out http://piwik.org/docs/javascript-tracking/. Interestingly, Piwik also provides an alternative approach using a specialized tracking API.
Last but not least, a quite interesting demo site of Piwik can be found at http://demo.piwik.org/.
With google-analytics one can track ones website's vistors in various complex ways. The google-analytics tracking service is intuitive and free (up to 5 million hits per month). This solution will show how to implement the necessary functionality in ones website.
Step 1: go to the google-analytics website.
Step 2: register and login.
Step 3: place the provided javascript snipplet directly before the end of your webpage's body segment.
Here the snipplet (from 11/2010). The XXXXXXXX-X will be replaced by ones account number.
javascript start
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-XXXXXXXX-X']);
_gaq.push(['_trackPageview']);
(function() {
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
})();
javascript end
That's it! But keep in mind that Google uses the information to extend its information about the visitor as well (privacy!).