You might see referral traffic coming from search engines like Google or Bing, a blog, newsletter, or email or social media sites like Facebook. Referrer traffic could be organic or through a paid search like cost-per-click (CPC) advertising or a paid advertising campaign that you have created (but in many cases, the paid advertising will show up in its very own Paid traffic type).
Direct traffic refers to traffic you receive to your website that doesn't come through any other channel. So, when you type www.hubspot.com into your search bar and hit 'Enter,' you're accessing HubSpot.com via direct traffic. If someone posted a link to www.hubspot.com on Facebook, however, and you clicked on that link, your visit would be bucketed in HubSpot.com's social media sources.
The term “organic traffic” is used for referring to the visitors that land on your website as a result of unpaid (“organic”) search results. Organic traffic is the opposite of paid traffic, which defines the visits generated by paid ads. Visitors who are considered organic find your website after using a search engine like Google or Bing, so they are not “referred” by any other website.