Google Analytics is the best tool for tracking website traffic. There is a java code used for tracking traffic. You have to include this code in the header of the website and then you can track the traffic as well as traffic sources by login through google.com/analytics/webs.
Google Analytics gives you three major facilities;
• Track Traffic of the website.
• Track resource of the traffic.
• Set Goal for tracking conversion rate of the website.
As an internet marketed I am using this tool for many of my projects. It helps me for tracking overall performance of the website.