Referral traffic is the coveted “word of mouth” recommendation. Referral traffic can also be a subset of organic traffic. But opposite of organic traffic’s “come one, come all” attitude, referral traffic “visitors to your site come from direct links on other websites rather than directly or from searches.” This is where back-links become very important. Back-links are valuable because other websites and blogs are citing your website as a credible source. Back-links to your website put you in good terms with SEO as well.