When a visitor clicks a URL in an email newsletter, or in a paid search ad, it will show as a “Direct Entry” in your Analytics Suite. Looking at your analytics reports, you will not be able to tell if the email newsletter or paid search ad (or Display ad, etc.) has made a positive impact on your website.
Tracking campaigns ensures that you will be able to tell exactly how many visits were generated with each campaign, how many pages the visitors looked at, the bounce rate, and also the conversion rate to your Goals, and the revenue generated by these visits.
Tracking campaigns is a very important part of understanding your websites’ performance.