Referral traffic is used to describe visitors to your site that come from direct links on other websites rather than directly or from searches. For example, other sites that like what you have to say or sell may post a link recommending your site. You can also try to drive your own referral traffic by leaving links on other blogs or forums you have joined. Pay per click ads also count as referral traffic.
Whether you're running a blog or a commercial site, you've probably often heard the term "Referral traffic" thrown around as something that can boost your visitors or sales. Referral traffic is not easy to obtain, but if you can get it, it can help you reach your readership or sales goals.