When the world is crashing around you, trust the data. Dive into Google Analytics and try to pinpoint where things went south. Think back on marketing tactics you recently pushed live and find the correlation. This should lead you to an internal audit, where you may discover an internal tool is broken or an external force is impacting your site. - Kirk Deis, Treehouse 51
To track website traffic you need analytics software. That anonymously logs every visitor to your site and keeps track of their actions. One of the most popular analytics apps is Google Analytics. It’s free, but there can be a learning curve in getting it set up correctly. If you don’t add your tracking code the right way, then you won’t be able to track your traffic. Consider getting an analytics expert to help you create the right setup for your website.
Another great way to get traffic is to join the social sites. They are popping up at an ever-increasing rate. By socializing with others on the net through these sites, everything you join or participate in gives you more people to see your site. And, if you're selling stuff from your site, you'll want to go to the places (interest groups) on the social site where people are interested in what you're selling.

Web traffic is the amount of data sent and received by visitors to a website. This necessarily does not include the traffic generated by bots. Since the mid-1990s, web traffic has been the largest portion of Internet traffic.[1] This is determined by the number of visitors and the number of pages they visit. Sites monitor the incoming and outgoing traffic to see which parts or pages of their site are popular and if there are any apparent trends, such as one specific page being viewed mostly by people in a particular country. There are many ways to monitor this traffic and the gathered data is used to help structure sites, highlight security problems or indicate a potential lack of bandwidth.